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In this work an intelligent web service environment for managing hydroponics cultivation processes is proposed. The environment is called HydroNet and includes information and personalized support to hydroponics' interested groups. The aim is to give the producer the opportunity to access for the first time hydroponics consulting services that meet his/her particular needs over the web. The environment consists of an underlying web services infrastructure. It supports training, support and recommendation services, adaptive web and user interaction services, remote online access services and GIS support services. The web services are coupled with smart mechanisms such as dynamic information flow, interface adaptation and intelligent web structure reorganization. The exploitation of various state of the art technologies takes place, in order to achieve a user centric approach for the collection, presentation and dissemination of data. Overall the environment aims at encouraging the development of hydroponics in Greece.
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HydroNet: An Intelligent Hydroponics Web Service Environment
A. Liopa-Tsakalidis1, E. Sakkopoulos2, D. Savvas3, A.B. Sideridis4, J. Tzimas5
1 National Agricultural Research Foundation, Institute of Plant Protection, L.
Amerikis and National Road, P.O. Box 5149, Patras 26004, Greece
2University of Patras, Computer Engineering & Informatics dpt, Patras 26500, Greece
3Technological Educational Institute of Epirus, Faculty of Agricultural Technology,
Department of Floriculture and Landscape Architecture, P.O. Box 110, Arta 47100,
4Agricultural University of Athens, Informatics Laboratory, 75 Iera Odos, Athens
11855, Greece
5University of Patras, Computer Engineering & Informatics dpt, Patras 26500, Greece
In this work an intelligent web service environment for managing hydroponics
cultivation processes is proposed. The environment is called HydroNet and includes
information and personalized support to hydroponics’ interested groups. The aim is to
give the producer the opportunity to access for the first time hydroponics consulting
services that meet his/her particular needs over the web. The environment consists of
an underlying web services infrastructure. It supports training, support and
recommendation services, adaptive web and user interaction services, remote online
access services and GIS support services. The web services are coupled with smart
mechanisms such as dynamic information flow, interface adaptation and intelligent
web structure reorganization. The exploitation of various state of the art technologies
takes place, in order to achieve a user centric approach for the collection, presentation
and dissemination of data. Overall the environment aims at encouraging the
development of hydroponics in Greece.
Intelligent information environment, web services, hydroponics, hydronet.
Plant cultivation in greenhouses is internationally based ever increasingly on
automated control systems. The existing infrastructure in contemporary greenhouses
allows interconnection with information management environments. Consequently
careful and intelligent integration using advanced information and communication
mechanisms would assist the producer to record, classify, manipulate and receive
advise about various data connected to various applied techniques such as yield data,
disease control, plant physiology and market conditions. The result is improved yield
and increased quality production. In this work we propose an intelligent environment
for managing hydroponics cultivation called HydroNet1 (see information views in
Figure 1). It is based on web services (Web Services, W3C, 2004), filtering
algorithms (Chakrabarti et al, 1999; Kleinberg, 1998) and it intends to boost
production rates, facilitating the use of information technology hydroponics’
1.1. Previous Work
There is sufficient work in the international literature today that could be used to
design an integrated, effective and useful hydroponics’ cultivation management
environment. Studies which are referred to indicatively are those of Acher et al.,
(1997); Adams and Massey, (1984); Adams and Ho, (1989); Daum and Schenck,
(1998); De Kreij, (1995); De Kreij and Van Os, (1988); De Kreij et al., (1997); De
Rejck and Schrevens, (1997a), (1997b), (1998a), (1998b), (1998c), (1999); Graves,
(1983); Liopa-Tsakalidis et al., (2000); Ohtani et al., (2000); Mavrogiannopoulos et
al., (1999); Raviv et al., (1998); Runia, (1995); Savvas and Passam (2002) Schwartz,
(1995); Sonneveld, (1981), (1982); Sonneveld and Straver, (1994); & Sonneveld et al,
(1999). A much more complete comparison in the bibliography sources which could
be used for this purpose is given by Hannan, (1998) and Savvas, (2001a, 2001b).
Systematic research is already taking place in Greece regarding the issue of automated
hydroponic cultivation management (Savvas and Manos, 1999; Savvas and Adamidis,
1999; Savvas, 2002a; Savvas, 2002b).
1.2. Hydroponics Overview
Today, hydroponics is defined as every plant cultivation method above ground with or
without the use of some solid sub-layer as a means of plant root growth, which is
completely based on liquid fertilization (fertigation) via a complete nutrient solution
to meet the water and nutritional requirements of plants. Hydroponics’ cultivation
constitutes an alternate cultivation method for vegetable and ornamental plants in
greenhouses, which presents very few disadvantages and many advantages such as:
Radical root disease management of greenhouse cultivation.
There is no need to combat weeds, which compete with cultivating plants.
There is no need to disinfect the soil.
Reduction in pesticide application and consequently production of healthier
vegetables and flowers.
Management of fertility problems, which appear in many greenhouse soils.
Control and monitor of desired minimum temperature in the root environment
may be more easily achieved and at a lower cost, granted that the plant roots
grow within a restricted mass of the substrate or into nutrient solution.
Plant nutrition is much more precise; it can be controlled and monitored more
efficiently and reliably. Moreover it can be readily and quickly readjusted in
the case of an error.
Plant cultivation above ground saves the grower from soil preparation.
The better physical and chemical properties of the substrate in comparison
with the soil, the optimal nutrition and capability of keeping higher
temperatures in the root layer during the annual cold season finally result in an
increased yield in hydroponics cultivation.
1 In order to find additional information concerning the HydroNET environment please visit
The hydroponics cultivation may include recycling of the run-off solution and
consequently the restriction or even the elimination of nitrate pollution
In reality, the basic disadvantage of hydroponics concerns the fact that it is a
cultivation method, which is based on the application of modern technology and
equipment and consequently requires know how.
1.3. Motivation
In countries where hydroponics is developed, the problem has been resolved by
means of developing efficient advisory support systems provided to farmers, by the
public service authorities, but also by the private sector too. In all such cases, the
advice support to farmers is based on the existence of standardised information
systems, through which individualised layouts are designed for each producer and the
necessary re-adjustment of nutritient solution is decided during the course of
In Greece, until now, there is nothing similar and as a result, various agricultural
supplies providers, who are active in this sector, are co-operating with European
private agents in order to acquire scientific and technical support. This is not a
flexible nor efficient solution, because the consulting services offered do not follow
the curve of the farmers needs.
It is obvious from the above that there is a necessity for the development of an
integrated information management environment for the support of hydroponics
cultivation by taking into account the Greek reality in the fields of greenhouse
1.4. Technologies involved
Web application development is a multi-facet activity involving different players with
different skills and goals (Ceri et al, 2000). In order to achieve coherence and
successful results, several years’ now standardized representation is used for both
static and dynamic web enabled solutions. Therefore current trends impose both the
use of XML schema (XML, 2004) representations of the web applications’ structure
and a combination of hypermedia design techniques such as the Object-Oriented
Hypermedia Design Method (Schwabe and Rossi, 1995). This synthesis of methods
allows standardization and separation of concerns that is a key requirement for any
Web modeling procedure.
The aim is to give the producer the opportunity to access for the first time
hydroponics consulting services that meet his/her particular needs over the web. To
achieve this, the proposed environment infrastructure is based on web services
mechanisms. Besides the standardization and wide availability to users and businesses
of the Internet itself, web services are also increasingly enabled by the use of the
XML as a means of standardizing data formats and exchanging data.
A web service environment is built in a step-by-step process supporting an
incremental or prototype process model. Each step focuses on a particular design
concern, and an object-oriented model is built. Classification, aggregation and
generalization/specialization are used throughout the process to enhance abstraction
and reuse.
This work is presented in the following sections as follows: In section 2
requirements that have to be fulfilled are presented. In section 3 the functional and
operational specifics are described. In the sequel the architectural aspects and the
functional details of the HydroNet solution are described within section 4. In the
following section 5, implementation issues of the environment are outlined. In section
6 the design of the evaluation and testing procedures is described. In section 7 final
conclusion and future steps will be found.
Successful development and adoption of information technology mechanisms requires
careful planning and a clear understanding of potential users and the technology
environment in which the solution will be employed.
After a series of thorough discussions with potential users of HydroNet and the
distribution of a number of short questionnaires carefully designed by a team of
software designers and hydroponics’ specialists we obtained that the solution needed
be user-friendly in order to initiate as much as possible cultivators
be personalized on the various users computer skills and personal cultivation
be interactive to cover the personal cultivator’s needs,
advise in form of diagrams, illustrations, tables, graphic figures,
provide a personalised e-learning module based on the capabilities of the
efficiently handle and interpret the increasing amount of data required to
implement hydroponics cultivation,
be high-speed and lightweight in operation in order to cost as less as possible
for internet access,
support multimedia data in order to present hydroponics techniques,
ensure the safety of data in different levels (user accessibility depending on
their code, e.g. administrator, editor, consultant, user, etc.),
allow simultaneous access control and synchronisation with local computer,
share data and information between consultants and growers,
provide remote management with the use of web browsers,
handle data transfer between a central database located on a desktop PC and a
number of handheld devices,
ideally include geographical information for the areas of operation,
be reliable and sufficiently robust to withstand the difficulties of greenhouses
data collection and
provide print options of the recommendations and other hydroponics
Web service network infrastructure allows the easy update of the environment.
Some additional requirements, which should be satisfied, are:
The continuous and unobstructed information update and propagation towards
the public.
The integration of the whole set of services under a uniform platform using a
friendly and easy to use interface.
The support of a strategic implementation, which will preview the system’s
geographic distribution, as well as its users’ increase (copying ability –
mirroring for the service’s use from more than one points, aiming public’s
faster access).
The efficient integration (economically and technically) of already existing
applications and products (e.g. databases).
Overall the potential users needed an adaptive web service environment with the
advice of which they would be able to implement efficiently hydroponics cultivation
Figure 1: Information view on HydroNET portal service
The aim of HydroNet environment is to cover a set of fundamental functions and
operations according to the specifications explained below.
3.1. HydroNet information and training portal service
The main goal is to inform and further train the cultivator regarding hydroponics. The
corresponding application content comprises a relatively large variety of data.
Introduction, general information and basic training regarding hydroponics are
constructively organised in order to allow ease of comprehension. The acclimatisation
of the user with the general function framework of a hydroponics cultivation is the
first goal to be achieved.
Another aim of the HydroNet portal constitutes in keeping the interested party
informed regarding the transition purpose in hydroponics, its advantages, its
disadvantages, and means of dealing with them, its demands, the species of
hydroponics’ cultivation and the disposable types of substrate cultivation.
The basic training module of HydroNet provides basic courses in hydroponics
cultivation for the new cultivators, in order to help them start working with modern
cultivation techniques. It supports personalization features to the educational topic
and the exchanging information flow in order to customize the educational process to
the learning curve of the trainee. This is accomplished by acquiring each user’s
learning model and activity choices. The educational profile is developed for each
trainee based on a questionnaire and continuously evolves according to the trainee’s
choices and activities.
3.2. HydroNet consulting service
The goal of this service is to provide adaptive support to the personal needs of the
cultivator concerning the greenhouse equipment and other establishment to enable
hydroponics’ cultivation.
The potential hydroponics’ cultivator gets the opportunity to introduce to the
environment a series of information regarding his/her individual cultivation specifics
and production aims, in order to receive corresponding examples and advice
(recommendations). The specific information that is usually introduced is:
the technical and financial data of the area,
the market the user prefers to address,
the geographic area where the greenhouse will be established,
the pre-existing infrastructures in transfers, transport, etc.
This service is a recommendation component allowing the user to provide details
and choices in order to get a proposal for an integrated design of a hydroponics
system that meets best his/her specific profile.
3.3. HydroNet recommendation service for integrated management of
hydroponics cultivation
3.3.1. Design of nutrition layout
Given the data of the related crop, the user will receive a suggested nutrition layout
for his hydroponics cultivation. More specifically, after logging into the system the
user is prompted to enter information such as the cultivated plant species, the plant
growth stage, the hydroponics system utilised (open or closed, sublayer type, etc.) the
mineral composition of the water used and the season of the year. Using a set of
alternative algorithms, the system makes a recommendation about the final nutrition
layout using various visualization forms (tables and diagrams), specifically designed
to be completely comprehensible even by non experienced users (required kilos of
fertiliser, target values of pH and electrical conductivity of the nutrient solution which
will be supplied to the plants, frequency of supply).
3.3.2. Readjustments and corrections in nutrition layout in the course of cultivation
By entering the data of chemical analyses from the root zone (nutrient solution or
water extract from the substrate), the growth stage of cultivation, the application or
not of recycling devices and possibly some of the cultivator’s preferences, the user
will receive specific suggestions to re-adjust the nutrition formula that has been
followed until then, in an absolutely comprehensible and applicable form.
3.3.3. Regulation of environmental conditions in the greenhouse
By providing the corresponding information, the user can be informed by the system
about the best environmental conditions for certain cultivations, as well as their
successful cultivation methodologies keeping focus in hydroponics.
3.3.4. Problem solving
A complete diagnostic and problem-solving guide is supported by the system. This
service provides a timely and effortless solution for the identification of objective or
subjective reasons causing various problems in hydroponics’ cultivation. The use a
step by step wizard provides a user friendly and thorough problems identification and
solving tool, maximising the performance of the farmers cultivation. Such problems
may be nutrient deficiencies or toxicities, physiological disorders due to unfavourable
environmental conditions, problems due to insufficient or excessive humidity in the
root region, unsatisfactory plant growth and low production due to incorrect crop
management or other use, etc.
After clarifying the set of specifications, the design and architecture of the
environment follow. HydroNet environment includes five (5) main component
modules, a) the web service infrastructure which is the core environment, b) the
collaboration and learning layer that retains, manages, distributes and delivers
hydroponics information, c) the adaptive web interactive module which enables
personalization of the users’ browsing experience, d) the remote access component
that enables the use of handhelds and e) the geographic information layer that enables
GIS information flow into the environment. Altogether the modules facilitate the
above presented functional business logic in order to assist the potential user in the
hydroponics’ cultivation procedures. The overall architecture can be found in Figure
2. In the sequel details concerning the architecture are presented.
Figure 2. HydroNet Architecture
4.1. HydroNet Web services infrastructure – core
Current approaches in distributed computing are not sufficient to completely meet the
needs for cross-platform application-to-application integration. The present trend is
moving away from tightly coupled monolithic systems towards systems of loosely
coupled components. The web services concept was designed to meet these
requirements of business-to-business application interaction. Web Services are based
on a set of open, platform independent standards such as XML (XML, 2004), SOAP
(SOAP, 2004), WSDL (WSDL, 2004), UDDI (UDDI, 2004) and HTTP (HTTP, 2004)
in order to reach a high level of acceptance. They have marked current web
engineering methodologies and are ubiquitously supported by IT vendors and users.
In short they are interoperable software components that can be used in application
integration and component based application development.
Web Services use XML-based messaging to exchange data between the web
service and the consumer. One of the core characteristics of a web service is the high
degree of abstraction that exists between the implementation and consumption of a
service. Web services allow applications and Internet-enabled devices to easily
communicate with one another and combine their functionality to provide services to
each other, independent of platform or language. Web services are characterized by
SOAP messages used to talk to a web service, WSDL files that describe a web
service, and the UDDI used to find Web services. Conceptually, web services are very
understandable. They eliminate many of the complexities that have been required
when there is a need for computer applications to interact with each other.
In this case, potential HydroNet users need an environment ready to deliver their
demands in an autonomous and 24x7x365 time frame availability, in order to support
hydroponics’ processes any time of the day effectively. On the other hand it is
resource-expensive to support separate dedicated machines for each necessary service
of a hydroponics management environment, because this would complicate the users’
data interaction and bring a network management overhead on the environment
(synchronization of cultivators’ accounts, nutrition & yield data manipulation per
geographic position etc)
In order to face the dilemmas posed by the described relationships we have
implemented a solution with the use of XML web services (see Figure 2). We believe
that we have faced in this way all of the previously named operational discomforts.
The proposed web services architecture allows the participation of a numerous simple
local systems each one located in a geographic region of the country. These servers
can be low cost web servers and they will provide a lightweight access to the main
services of the environment with the use of web services. Our solution is cost-
effective, because it out-sources the different services, that hydroponics’ interested
cultivator needs, through a simple web information server to the main web services
providers. In this way only the web service provider host will have to be a main-frame
machine, while the user will have a quick and efficient interaction with a web
information server close to its access position.
The included web services provide informational only functions for the
hydroponics’ interested group and together complete functionality for hydroponics’
activated farmers based in a common standard way (protocol SOAP and XML). There
is no need for the local web informational system to get to know and to intervene
directly with all the internal hydroponics’ core environment. The informational
services of such type allow full functionality for the potential user, without having
direct access in the central system but through transparent web services.
The use of this emerging technology, XML web services, allows the very rapid
incorporation and support of several activities, including interconnection with third
party service providers such as chemical laboratories, weather forecast centers or
other agricultural partners. It simplifies and accelerates the process of communication.
4.2. Hydronet collaboration and learning service
This is the main service of HydroNet and it comprises a) a collaboration service that
allows the communication between hydroponics farmers and specialists as well as
several supporting hydroponics information and b) the training, supporting and
solution recommendation service.
4.2.1. Hydronet Intranet service - Hydranet
A web service based CSCW (Bouras et al., 2000) environment facilitates the
collaboration between hydroponics researchers, as well as provides electronic means
of communication and collaboration between farmers and the supporting
hydroponics’ research community. This service enhances the communication link
between cultivators and researchers providing means for:
Publishing and finding information easily.
Working productively in teams.
Connecting effectively with others.
Providing a consistent user experience.
The CSCW environment, called Hydranet, provides a range of intranet
capabilities (Garofalakis et al., 1999a) thus optimizing the collaboration effectiveness
between the various groups of users. Some of the system features are:
Delivery of personally relevant information through audience targeting and
through personalization and customization tools.
Teams are able to publish new content to the portal, helping to preserve
knowledge and expertise for the future.
The users have access to various Document Libraries according to their access
privilidges. Documents stored across all document libraries are fully indexed
and searchable. The users can create, edit, and upload documents, check
documents in and out, and track past versions of documents.
HydraNet stores lists of information, including announcements, tasks,
contacts, and custom lists. Additionally, a search option is supported for
searching the contents of lists across the system.
Provision of collaboration tools and services to users, for either collaboration
on documents or for resources relevant to meetings.
Support of Audiences. An audience is a group of users with similar roles,
interests or tasks. The system uses audiences to deliver targeted content to
Support of Topics. To make information easier to find, Hydranet organizes
information into topics that contain similar content.
Alerts messages that inform users when content that they are interested in
changes in some way. Alert messages are delivered in an e-mail message or in
a Web Part on HydraNet. These alerts help users stay current with the latest
version of the content that is important to their work.
Support of different user profiles.
Support of advanced full text search for different formats within Hydranet.
The system supports multiple browser-based management tools, including a
browser interface for area managers to manage their areas.
To ensure data integrity of the main storage database, a role based access control
model (Sandhu et al., 1996) is applied.
Figure 3: Support and recommendation information
4.2.2. Training, support and recommendation service
The prime objective of this service is the creation, operation and the support of the
hydroponics learning and support process. The service should not be merely perceived
as a distance learning application in the sense that people can remotely access relative
information. The focus is rather placed on setting up an electronic community of
learners and hydroponics’ specialists that are provided with the necessary IT tools for
communicating with each other in order to promote hydroponics efficient cultivation.
(Rigou et al., 2004; Garofalakis et al., 1998)
The service assumes three discrete profiles: farmers/ cultivators, hydroponics’
specialists and administrators (the first two compile with the available training
structure; the last one with the system’s operation). Trainees (cultivators) are the main
target group, as they are to use the service for learning and getting advice. Specialists
recreate and determine the structure of the learning and the recommending modules
and incorporate them in the service. They also provide feedback to trainees directly.
Administrators are responsible for service configuration and maintenance, as well as
for network management.
The social requirement of the learning community concept is two-fold:
synchronous and asynchronous, with each mode contributing to various scenarios of
communication and collaboration. In order to facilitate asynchronous communication,
the system provides the means for message exchange through the “Forums”, the
“Questions & Answers” or the “Get Personal Advice” facilities (preview in Figure 5).
On the other hand synchronous communication was also considered essential for
creating a sense of directness, thus the Chat facility was incorporated.
The service underlying architecture (as depicted in Figure 4) is composed of three
distinct layers. The core layer provides basic service functionality and in this
framework it facilitates the file system, the database system and a web service
interface. The learning modules are divided into lessons and topics. The database
system is used to store a variety of data. It holds personal data on the user profile. The
records for the tutors and the trainees are also located there. It also contains the
required information for describing the schema of the learning modules. Finally, it
holds data relevant to both the design and the content of the Forum, the Questions &
Answers and the Bulletin Board services. The chat server synchronizes the
communication among users that takes place via the chat mechanism. It manages the
messages exchanged between the users, making sure that all messages are delivered to
the appropriate recipients.
The web server accepts user requests returning the corresponding data back to the
user. The returned data are not statically stored in web pages, but are constructed on
demand by information maintained in both the file and the database system.
The system focuses on hydroponics interested farmers group and for this reason it
offers several capabilities related to the learning modules. It also offers diverse
support and assistance methods, search facilities and a number of other services. The
learning modules are divided into trainings and topics. A trainee can read and
download these topics. The system provides a print-friendly version of all the topics
comprising training as a separate file, so that the trainee can download or print it. In
addition, the trainee can mark topics already studied to his/her personal progress
record. Topics marked as read, display an informative message to the trainee
suggesting to move on to a topic not completed yet. Trainees can also view their
individual progress, in order to have a more general view of the progress of the
learning process.
Specialists can manage the learning modules through the web interface. They can
structure and upload a module or a part of a module. They can also update the on-line
glossary of the system while they are completing all the learning modules. Recorded
lectures (in streaming video format for faster client delivery) can be posted to the
system. Text announcements can be also posted.
Core Layer
Interaction Layer
File System
Records Specialists
Available Advice
Board &
Forum Course
Server Communication Server
Figure 4. Training, supporting and recommending service
4.3. HydroNet adaptive web and user interaction service
HydraNet and the training and support service are end-user services that provide
specific solutions in certain farmers’ questions and needs. However, in order to have
an efficient HydroNet environment several more supporting web services handle
intelligently the web browsing behaviour, the presentation of the information portal
service and the overall information flow of the environment. Specific intelligent
mechanisms and techniques provide added-value services to the main web services of
Hydronet. The corresponding details follow.
4.3.1. Dynamic information flow to HydroNet users
All cultivators and hydroponics specialists receive key characterization in the user
profile according to interests deriving from their topic accesses. Once a web page is
updated with new material concerning a specific topic, the users who had with certain
frequency expressed interest on it in the past are informed about the changes. Thus
instead of making the users go after recently updated web pages, it is desirable to have
information selectively flowed to them. This is called information filtering (Hanani et
al, 1999). In this case we address the collaborative filtering method, which is the
filtering of information based on the advice of others. The users are not only informed
of the recently updated topics that they have visited quite often in the past, but also for
those topics that have been accessed with certain frequency by other users belonging
in the same group of interest with the first ones. In particular, the profile of the users’
information needs is captured through their classification in groups of interest.
The classification of the users into subsets according to their path traversal and
page accesses will be achieved by using the spectral filtering method (for the
mathematical details of the approach see Chakrabarti et al, 1999; Kleinberg, 1998).
The initial motivation for the development of the method was the discovery of high-
quality topical resources in hyperlinked corpora. The full power of the approach is
visible when being applied on entities other than hyperlinked documents. In our
paradigm we have two kinds of entities: web objects and users accessing them. The
precise notion of “access” refers to frequency of access.
Following, we will only outline the method of spectral filtering, as it is applied in
our environment (further details concerning the mathematical details of the approach
see (Bharat & Henzinger, 1998; Chakrabarti. et al, 1998; Chakrabarti et al., 1999;
Kleinberg, 1998). Let S1 denote the set of users and S2 denote the set of web pages
corresponding to a specific section. We associate with each ordered pair (i,j) of
entities in S1 and S2, a non-negative real-valued affinity A[i,j]. Typically, we set A[i,j]
to be a well-chosen function of the accesses user i performs on page j. The A[i,j]s
constitute an n x m matrix A, each of whose rows corresponds to users and each of
each column to web pages. The entries of the matrices AAT and ATA can be viewed
as expressing the similarity between different users and web pages respectively
(where the notion of similarity is deduced from similar patterns of accesses). The
matrices AAT and ATA are both real and symmetric and their eigenvectors have only
real components. Moreover they have the same set multiset of eigenvalues. Let xs1, xs2
be two eigenvectors of AAT and ATA respectively corresponding to the same
eigenvalue. We can view the components of each eigenvector as assigning to each
entity a position on the real line. We deem the entities with large positive values in an
eigenvector to be a cluster, and the entities with large negative values to be a different
cluster. Alternatively, we can examine the values in the eigenvector (in sorted
increasing order). At the largest gap between successive values, we declare a partition
into those entities corresponding to values above the gap, and those entities with
values below. From the above discussion it follows that the eigenvectors xs1, xs2
provides us with two pairs of interrelated clusters (c1,c1), (c2,c2) where ci
corresponds to a group of users with similar web-access patterns and ci corresponds
to the web pages that interest the users in the ci group.
Following the above partitioning process for all the non-principal eigenvectors
enables us to group the users into subsets with similar preferences and to map the
entities of each subset to the web pages that are of interest to them.
4.3.2. Interface adaptation
Due to the many and diverse requirements and limitations dictated by the potential
users, the design of the interface was treated as a primary concern. To avoid
developing various independent versions, we decided to take an adaptive approach to
the issue; core functionalities and internal data dependencies were implemented at a
lower level and then another (architecturally upper) layer was assigned the
responsibility of constructing and delivering to the user the adequate view depending
on individual preferences and skills (Destounis et al., 2004).
A critical aspect in the attempt to provide more effective and higher quality
interaction between humans and artifacts has been the notion of metaphors (e.g.,
Carroll et al., 1988; Henderson et al., 1986; Moll-Carrillo et al., 1995). Metaphors in
human communication are essentially mechanisms for explaining concepts by
example. In metaphors, concepts in a source domain are mapped to concepts in a
target domain on the basis of some similarity between the two domains (Ueda,
2001).Whereas in the past the use of metaphors was at the discretion of the designer,
or in the best of cases, bound to what the underlying development toolkit offers (i.e.,
trashbins, form filling), today and for certain non-traditional / non-business
applications, embedding metaphors to interface design is compelling for the wide
adoption and user acceptance of the application (Stephanidis and Akoumianakis,
1998). A metaphor may be used at various levels, ranging from the overall interface
design offered by an application, to the task level (i.e., how users engage and perform
specific goal-oriented activities), as well as the physical level of interactions (i.e.,
icons used to convey intended meaning).
In many cases it is important to use even variants of a metaphor in the context of
the same application (i.e. for better representing specific tasks) thus leading to the
notion of multiple metaphor environments firstly introduced in the context of
FRIEND21 (Ueda, 2001), a major collaborative R&D project which proposed a set of
guidelines and a conceptual depiction of architectural components for the next
generation human interface. One of the key concepts in this effort was the notion of
metaware. According to this theory (Stefanidis, 1999), ‘the computer can exhibit
adaptive behavior in the sense that it can select and present appropriate images to
assist the user in executing tasks, based on functions for identifying task intentions
and the context of use, as this is provided by the user’s personal operation history,
preferences and dislikes’.
4.3.3. Intelligent reorganization service
This service focuses on reorganizing methods of web information structures, based on
user behaviour. We base the reorganization on the fundamental ideas outlined in
(Garofalakis et al., 1999b). According to that method, the number of hits a page
receives, as those are calculated from log file processing (see Drott, 1998 for an early
analysis on web logs), is not a reliable metric to estimate the page’s popularity. Thus a
refined metric is proposed, which takes into account structural information. Based on
this new notion of popularity, reorganization of certain pages is proposed. After
performing some reorganization steps, they also observed an overall improvement to
site access.
Figure 5: Recommendations and Personal Advice on hydroponics with HydroNET
This service compiles the structural information of the HydroNet portal of the
geographically located web servers according to the above web logs processing
method. This way each web information portal replica delivers an interface adapted to
the needs and interests of its local farmers/ users.
Figure 6: Example of reorganization results according to web logs.
Beside the underlying adaptation services there are also some added-value
services that enable interfacing with advanced information management systems such
as a) mobile data input and reporting devices as well as b) geographic information
data warehouses. These added-value services are also web service based in order to
maintain the possibility to be out-sourced.
4.4. HydroNet palm-top remote online access service
For many years, users have requested an electronic device that can be taken into the
field to streamline the data entry process, run models of pest development, generate
in-field reports of pest status, access historical data for insects and crops, and most of
all, save time. To address this, several of the Hydronet management components are
suitable for browsing through handheld devices that support mobile browsing
Previously, users had to write the information they collected in the field on paper,
then fax it to a local hydroponics specialist. The mobile environment helps with
maintaining data integrity, consistency when there is more than one person collecting
information, and time savings in collating information for management decisions. The
system specifications, software development, delivery, and the application of the
handheld system are described.
In brief, the remote online access system would allow (a) in-field recording and
analysis of specific hydroponics data; (b) provide a report of current hydroponics’
process status; and (c) have the capacity to download and store data for the future
steps of the hydroponics process.
4.5. HydroNet GIS support service
This service is a spatial module interfacing with a geographic information system to
generate spatial information regarding agricultural fields (Sirmakessis et al., 1997).
Spatial data used in hydroponics’ management planning may include fields, streams,
ditches, buffers, wetlands, digital raster graphic, soils (soil survey geographic data
set), etc.
The workflow involves four sequential processes, namely (1) generate/acquire
spatial data; (2) enter attributes for spatial data; (3) create setback (buffer) areas; and
(4) analyze and extract information. The starting point for this module is to gather or
develop all spatial data required.
It also computes the area percentage of each map unit symbol covering each
selected field. The service has interface to connect to geographic database in order to
retrieve soil physical, chemical and water feature properties and generates soils
reports for selected fields.
The component services that comprise HydroNet follow the service oriented
architectural approach. In the following sections details of this implementation
approach are given. Additionally discussion of the remote access service and the
spatial information service is presented.
5.1. Service oriented approach
HydroNet is a large-scale web service environment, based on Microsoft .NET
technology (currently running on .NET framework 1.1) (an overview is offered in
DOTNET, 2004). Moreover Web Services Enhancements for Microsoft .NET (WSE)
is used. It is an add-on to Microsoft Visual Studio .NET and the Microsoft .NET
Framework providing developers the latest advanced Web services capabilities to
keep pace with the evolving Web services protocol specifications.
The application designed by SOA is based on services that interact with business
components. Each service defines a particular business function. These services
interact with each other to accomplish hydroponics’ processes.
This service-based design provides the key to flexibility. It allows functions that
are designed, implemented, and exposed as services to make use of other services
regardless of where they are, on which physical machine they are deployed, and so
on. These services aggregated define a system consisting of organizational functions
and, when exposed to each other, business relationships.
The web services architecture (also known as Service Oriented Architecture abr.
SOA) (SOA, 2004a; SOA, 2004b) is beneficial in the proposed hydroponics
environment because:
Complexity is hidden from the consumer of the service.
Components can reside on any machine, anywhere in the world and still
be accessed the same way.
Developer roles are focused on a specific development layer.
Development can be done in parallel.
The service definition supports multiple client types both typical web
browsers and advanced palm-top browsers.
More re-usability of components across the heterogonous platforms is
possible. There are no language and platform integration problems when
the functions are defined as services.
5.2. HydroNet palm-top remote online access service
One of the biggest obstacles to writing device applications today is that most devices
require learning different APIs than those for desktop applications. .NET Compact
Framework uses the same .NET Framework programming model and the same Visual
Studio .NET development tools that developers are already using on desktops and
servers, as a consequence it greatly increases developer effectiveness. It is also the
only mobile development platform with native support for XML Web services (XML,
2004 and Mobile.Net, 2004).
The problem with web-enabled devices is that each one can potentially have its
own display issues and capabilities, as well as using a variety of different markup
languages. The mobile internet toolkit, an add-on for Visual Studio .NET, provides a
solution that can allow developers to greatly streamline their approach to targeting the
variety of mobile devices currently on the market, as well as being able to easily
handle any new ones that come out in the future.
5.3. HydroNet GIS support service
In order to support GIS interface HydroNet provides collaboration with Autodesk
MapGuide 6.5. In this way Hydronet helps to manage, and distribute GIS broadening
the access to mission-critical geospatial data.
It allows streamline data distribution and decision support. Compete better
through faster decision making, reduced operational expenses, improved customer
service, and streamlined data maintenance. This proves especially valuable for
environments with large mobile workforces.
This is the last part of the HydroNet implementation details. Following there is
the description of HydroNet testing and evaluation procedures.
For the evaluation, user testing was considered as the most appropriate method as in
our case only members of the target group along with specialized personnel were in
position to provide valuable feedback, identify problems and suggest modifications.
Τesting and in-field evaluation is designed for a period of 6 months before the
formal release of the first version of the environment. The testers’ group (already 14
registered participants) varies in terms of cultivation region, the size of the
commercial enterprise, and the way they endeavour to use the software.
We plan a series of evaluation sessions using lab observation with at least four
groups of test users corresponding to the types of target groups, intending to have
more precise results on the systems’ performance. We also prepare a series of short
questionnaires in order to identify system the systems’ usability and performance
problems after the in-field testing.
For the lab observation a video camera is set to record the computer screens and a
special form is prepared so that the test modulator can write down remarks during
observation (moderation will be conducted by CHI specialists that will conduct the
evaluation in order to keep users relaxed and in a familiar ‘surrounding’). In addition,
two sets of questionnaires will collect quantitative and qualitative feedback, along
with two types of usage scenarios (novice/expert users), which are executed during
the sessions and are designed so as to cover all basic aspects of the primary tasks.
Possible fixes to the software and ideas for additional functionality may be
identified. The majority of these will be implemented before the release of the first
version. Along with the large-scale field evaluation, smaller trials are to be conducted
to assess the benefits of using the various modules.
The study and the HydroNet environment contribute to an integrated and more
efficient operation of hydroponics greenhouses with certain financial benefits which
will result from:
Excellent quality and competitive product within the country and abroad.
Programmed quantity and quality of product during the whole production
Energy saving due to brevity of the whole production process.
Innovation which aims at upgrading farming products in combination with
technological knowledge in a laboratorial and pilot scale.
Reinforcement of the virtually non-existent co-operative relationship between
scientific research and the production sector in our country, which signifies the
introduction of new technology in crop production and transmission of high-
level knowledge.
Web services provided by the expert environment are a very powerful tool,
particularly for inexperienced practitioners and those unfamiliar with the subject of
hydroponics. When used in conjunction with known modern cultivating techniques,
they can help refine the search for solutions and reduce the amount of time needed
when referring to the hydroponics’ processes.
Future steps and upgrades of the proposed environment may include:
integration of the system with various governmental and EU portals
providing critical information on farming in the several regions of the
development of sub-portals oriented to the cultivation of specific crop
species in order to avoid useless navigation within the Main HydroNet
development of interactive multimedia training tools that could be
provided to the various users for offline training in their houses without
the use of Internet,
provision of a fully personalized Main web page of the system providing
personalized news for each user,
We would like to thank all the fellow researchers that supported this work.
Acher, A., B. Heuer, E. Rubinskaya, and E. Fisher, (1997). Use of ultraviolet-
disinfected nutrient solutions in greenhouses. J. Hort. Sci., 72: 117-123.
Adams, P., and D.M. Massey, (1984). Nutrient uptake by tomatoes from recirculating
solutions. In: Proceedings, 6th International Congress on Soilless Culture. ISOSC,
Wageningen, The Netherlands: pp. 71-79.
Adams, P., and L.C. Ho, (1989). Effects of constant and fluctuating salinity on the
yield, quality and calcium status of tomatoes. J. Hort. Sci., 64: 725-732.
Bouras, C., Destounis, P., Garofalakis, J., Triantafillou, V., Tzimas, G., Zarafidis, P.,
(2000). A Cooperative Environment for Local Government: An Internet – Intranet
Approach. Telematics and Informatics journal.
Carroll, J., Mack, R., Kellog, W. (1988). Interface Metaphors and User Interface
Design. In Handbook of Human-Computer Interaction, M. Helander (Ed.), North-
Holland, pp. 67-82.
Ceri, S., Fraternali, P. and Bognio A., (2000). Web Modeling Language (WebML): A
modeling language for designing Web sites. WWW9, Amsterdam.
Chakrabarti, S., Dom, B., Gibson, D., Kleinberg, J., Kumar, S.R., Raghavan, P., Ra-
jagopalan, S. & Tomkins, A. (1999). Mining the Web’s link structure. IEEE
Computer 32 (8) pp.60-68.
Chakrabarti, S., Dom, B., Gibson, D., Kumar, S., R., Raghavan, P., Rajagopalan, S.
and Tomkins, A., (1998). Spectral filtering for resource discovery. In Proceedings of
ACM SIGIR Workshop on Hypertext Information Retrieval on the Web, Melbourne,
Bharat, K., & Henzinger, M. (1998). Improved algorithms for topic distillation in a
hyperlinked environment. In Proceedings of ACM Conf. Res. and Development in In-
formation Retrieval, pp.104-111.
Daum, D., and M.K. Schenk, (1998). Influence of nutrient solution pH on N2O and N2
emissions from a soilless culture system. Plant and Soil, 203: 279-287.
De Kreij, C. (1995). Latest insights into water and nutrient control in soilless
cultivation. Acta Hortic., 408: 47-61.
De Kreij, C., and P.C. Van Os, (1988). Production and quality of gerbera in rockwool
as affected by electrical conductivity of the nutrient solution. In: Proceedings, 7th
International Congress on Soilless Culture. ISOSC, Wageningen, The Netherlands:
pp. 255-264.
De Kreij C., W. Voogt, A.L. Van Den Bos, and R. Baas, (1997).
Voedingsoplossingen gesloten teeltsystemen (Nutrient solutions for closed cultivation
systems). Brochures 1-16. Research Station for Floriculture and Glasshouse
Vegetables (PBG), Naaldwijk, The Netherlands.
De Rijck, G., and E. Schrevens, (1997a). Elemental bioavailability in nutrient
solutions in relation to dissociation reactions. J. Plant Nutr., 20: 901-910.
De Rijck, G., and E. Schrevens, (1997b). pH influenced by the elemental composition
of nutrient solutions. J. Plant Nutr., 20: 911-923.
De Rijck, G., and E. Schrevens, (1998a). Elemental bioavailability in nutrient
solutions in relation to complexation reactions. J. Plant Nutr., 21: 849-859.
De Rijck, G., and E. Schrevens, (1998b). Elemental bioavailability in nutrient
solutions in relation to precipitation reactions. J. Plant Nutr., 21: 2103-2113.
De Rijck, G., and E. Schrevens, (1998c). Composition of the mineral composition of
twelve standard nutrient solutions. J. Plant Nutr., 21: 2115-2125.
De Rijck, G., and E. Schrevens, (1999). Guidelines to optimize the macrocation and
macroanion composition of nutrient solutions using mixture theory. J. Agric. Engng
Res., 72: 355-362.
Destounis, P., Garofalakis, J., Mavritsakis, G., Rigou, M., Sirmakessis, S., Tzimas,
G., (2004). Designing for Ease is Designing for All; Experiences from a Simplified
Office Suite. Information Technology & People Journal, Emerald.
DOTNET, Technology Overview of .Net Framework v1.1, Microsoft (2004). .
Drott M.C. (1998). Using web server logs to improve site design Proceedings of ACM
SIGDOC 98 pp.43-50.
Garofalakis, J., Sirmakessis, S., Tsakalidis, A., Tziavas, P., Tzimas, J., Vassiliadis, V.,
(1998). An Interactive Web-based Approach for Environmental Science Courses in
Secondary Education, in the Proceedings of the World Conference on Educational
Multimedia and Hypermedia & World Conference on Educational
Telecommunications (ED-MEDIA & ED-TELECOM 98).
Garofalakis, J., Kappos, P., Kondilis, T., Tsakalidis, A., Tsaknakis, J., Tzimas, J.,
Vassiliadis, B., (1999a). Communication and Collaborative Work via Intranet
Technologies. World Conference on the WWW and Internet, WebNet 99.
Garofalakis, J., Kappos, P. & Mourloukos, D., (1999b). Web Site Optimization Using
Page Popularity. IEEE Internet Computing 3(4): 22-29.
Graves, C.J., (1983). The nutrient film technique. Hortic. Rev., 5: 1-44.
Hanan, J.J., (1998). Greenhouses: Advanced technology for protected cultivation.
CRC Press, Boca Raton, Florida, U.S.A.
Hanani, U., Shapira, B. & Shoval, P. (1999). Information Filtering: Overview of Is-
sues, Research and Systems. User Modeling and User-Adapted Interaction, Kluwer
Academic Publishers, Netherlands.
Henderson, JR., A., Card, S., (1986). Rooms: the use of multiple virtual workspaces
to reduce space contention in a window-based graphical user interface. ACM
Transactions on Graphics, vol. 5(3), pp. 211-243.
HTTP, HyperText Transport Protocol (2004). .
Kleinberg, J. (1998). Authoritative sources in a hyperlinked environment. Proc.
ACM-SIAM Symposium on Discrete Algorithms.
Liopa-Tsakalidou A, Bonatsos D., Tzempelikou K, Konstantinidou-Doltsninis S.,
(2000). Qualitative characteristics of lettuce (Lactuca sativa L) variety Butter head
Rex RZ cultivated in hydroponic system. 8th Hellenic Conference on Botatany, Patra
5-8 October 2000.
Mavrogianopoulos, G.N., J. Spanakis, and P. Tsikalas, (1999). Effect of carbon
dioxide enrichment and salinity on photosynthesis and yield in melon. Scientia Hort.,
79: 51-63.
Mobile.Net (2004). Developing Applications for Windows Mobile,
Moll-Carrillo, Salomon, G., March, M., Fulton Suri, J., Spreenber, P., (1995).
Articulating a Metaphor Through User-Centred Design. In the Proceedings of the
ACM Conference on Human Factors in Computing Systems (CHI'95), Denver,
Colorado, New York: ACM Press, 7-11 May, pp. 566-572.
Ohtani, T., A. Kaneko, N. Fukuda, S. Hagiwara, and S. Sase, (2000). Development of
a membrane disinfection system for closed hydroponics in a greenhouse. J. Agric.
Engin. Res., 77: 227-232.
Raviv, M., A. Krasnovsky, S. Medina, and R. Reuveni, (1998). Assessment of various
control strategies for recirculation of greenhouse effluents under semi-arid conditions.
J. Hort. Sci., 73: 485-491.
Rigou, M., Sirmakessis, S., Tzimas, G., (2004). An Architecture for an Adaptive
Web-Based Learning Environment. in the proceedings of the IASTED International
Conference on Web-based Education (WBE 2004), pp. 637-641.
Runia, W.T., (1995). A review of possibilities for disinfection of recirculation water
from soilless cultures. Acta Hortic., 382: 221-229.
Savvas, D. and G. Manos, (1999). Automated composition control of nutrient solution
in closed soilless culture systems. J. Agric. Engin. Res., 73: 29-33.
Savvas, D., and K. Adamidis, (1999). Automated management of nutrient solutions
based on target electrical conductivity, pH, and nutrient concentration ratios. J. Plant
Nutr., 22: 1415-1432.
Savvas, D., (2001a). Nutritional management of gerbera (Gerbera jamesonii) grown
in a closed soilless culture system. Acta Hortic., 554: 175-182.
Savvas, D., (2001b). Nutritional management of vegetables and ornamental plants in
Hydroponics. In: Crop Management and Postharvest Handling of Horticultural
Products. In: Dris, R., R. Niskanen and S.M. Jain (eds). Science Publishers, Inc.,
Enfield (NH), USA. pp. 37-87.
Savvas, D., and H.C. Passam (Eds). Hydroponic Production of Vegetables and
Ornamentals. Embryo Publications, Athens, Greece: pp. 299-343.
Savvas, D., (2002a). Automated replenishment of recycled greenhouse effluents with
individual nutrients in hydroponics by means of two alternative models. Biosystems
Engineering, 83: 225-236.
Savvas, D., (2002b). Nutrient solution recycling. In: Savvas, D., and H.C. Passam
(Eds). Hydroponic Production of Vegetables and Ornamentals. Embryo Publications,
Athens, Greece: pp. 299-343.
Schwabe, D. and Rossi, G., (1995). The Object Oriented Hypermedia Design Model,
Communication of the ACM, Vol. 38, #8.
Schwarz, M., (1995). Soilless Culture Management. Advanced Series in Agricultural
Sciences, Vol. 24. Springer-Verlag, Berlin, Heidelberg.
Sirmakessis, S., Tsakalidis, A., Tzimas, G., (1997). A Distributed Object Oriented
System for Map Design and Production. in the Proceedings of the 3rd Joint European
Conference and Exhibition on Geographical Information, EGIS-AM/FM-UDMs
SOA, Web Services Architecture, W3C. (2004a). .
SOA, Service Oriented Architecture, Microsoft Corporation. (2004b). .
SOAP, Simple Object Access Protocol Reference Site (2004).
Sonneveld, C. (1981). Items for application of macro-elements in soilless culture.
Acta Hortic., 126: 187-195.
Sonneveld, (1982). A method for calculating the composition of nutrient solutions for
soilless cultures. Translated edition. Informatiereeks, No 57. Glasshouse Crops
Research Station Naaldwijk, The Netherlands.
Sonneveld, C., and N. Straver, (1994). Nutrient solutions for vegetables and flowers
grown in water or substrates. 10th Edition. Serie: Voedingsoplossingen Glastuinbouw,
No 8, 45 pp. P.B.G. Naaldwijk – P.B.G. Aalsmeer, The Netherlands.
Sonneveld, C., W. Voogt, and L. Spaans, (1999). A universal algorithm for
calculation of nutrient solutions. Acta Hortic., 481: 331-339.
Stephanidis, C., (1999). The GRAFIS Word Processor for People with Disabilities
ERCIM News No.38. Available at
Stephanidis, C., & Akoumianakis, D., (1998). Multiple Metaphor Environments:
Issues for effective interaction design. In Proceedings of the 8th ERCIM - DELOS
Workshop on "User Interfaces for Digital Libraries", Stockholm, Sweden, 21-23
UDDI, Universal, Description, Discovery and Integration Specifications (2004). .
Ueda, H, (2001). The FRIEND21 Framework for Human Interface Architectures.
Chapter 13 in User Interfaces for All, Concepts, Methods and Tools, Stephanidis, C.
(Ed.). Mahwah, NJ: Lawrence Erlbaum Associates.
Web Services, Web Services Activity Statement, WWW Consortium (2004). .
WSDL, Web Services Description Language Reference Site. (2004). .
XML, Extensible Markup Language (2004). .
... The Internet of Things (IoT) is a new information technology and the network of things that are connected to the Internet through corresponding sensing devices to enable data acquisition, fusion and processing and allow intelligent identification and management at the operating terminal. IoT is widely applied in fields like modern greenhouse environmental monitoring [3,4], agricultural product tracing [5], smart city [6], livestock and poultry farm environmental monitoring. For livestock and poultry farm environmental monitoring, [7] reported that AVR controllers were used to monitor the temperature, humidity, CO2 concentration and NH3 concentration inside a henhouse, the configuration software LabVIEW was used to design visual application software, and fuzzy control was used to regulate the temperature, humidity, CO2 concentration and NH3 concentration inside the henhouse. ...
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To monitor multiple environmental factors of henhouses in modern chicken farms, a henhouse online monitoring system based on wireless sensor network was developed using wireless sensor technology and computer network technology. Sensor data compensation and correction were designed to be achieved using software and data fitting methods, data reliable transmission achieved using a data loss recovery strategy, and data missing during monitoring addressed using a self-decision and online filling method. Operation test of the system showed that: The system was economic and reliable; it enabled wireless monitoring and Web display of the environmental factors of a henhouse; and the root mean square errors (RMSEs) between the estimated values from the self-decision and on-line filling method and experimental values of the four environmental factors were 0.1698, 3.0859, 77 and 0.094, respectively, indicative of high estimation accuracy. The system can provide support for modern management of henhouses and can be transplanted to related monitoring scenarios in the agricultural field.
... There is sufficient work in the international literature today that could be used to design an integrated, effective and useful hydroponics' cultivation management environment. Studies which are referred to indicatively are those of Jones & Terrill, 1984;Jones et al., 1992;Liopa-Tsakalidis et al., 2005;Lychak & Brown, 1995;Ntzanis, 2003;Palmer et al., 1993;Pearce et al., 1998;Pearce et al., 1999;Pfeiffer et al., 1990;Reed, 1996;Rideout et al., 1995;Smith et al., 1993;Smith et al., 2004;Stephenson et al., 1984;Walker, 1981;Walker & Reynolds, 1982. ...
... In addition, Rogers notes that innovations are more likely to be adopted if they are less complex, lend themselves to trialing and whose results are observable to others. Moreover, over the past two decades researchers have been increasingly recognizing the need to look at agricultural technologies as a package where farmers may adopt components at different times and speeds [3,8,10,14]. ...
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The purpose of this study is to describe an application that analyzes all the possible tasks a farmer makes in the field, from ploughing the soil, fertilization and use of herbicides, up to traceability of the agriculture products. Farmers are provided with smart phones and tablets for documenting their tasks and products in real time, so that they can use the Integrated Management System in an optimal way, ensuring practical, financial and environmental benefits. The agricultural products will be documented safely and stored in a central information point for future traceability. These documentations may follow the product till the consumer so that he has all the production information available. To achieve these goals a mobile information system is developed that includes amongst others decision support capabilities for the farmer. The system also offers mobile services so as to support the implementation of a whole network of producing units. © 2013 The Authors. Published by Elsevier B.V. Selection and peer-review under responsibility of HAICTA.
... Hu (2002) presents a methodology to combine Web services with an ontology in order to unify the underlying data subcomponents of an industrial control system. Liopa-Tsakalidis, Sakkopoulos, Savvas, Sideridis, and Tzimas (2005) have described HydroWeb, a system to facilitate hydroponic cultivation via Web-based training, communication with experts and online monitoring. Web Services were chosen as a platform to unify communication and application development from various sources of information. ...
A greenhouse provides an essential means of livelihood to its owner and must be economically practical for the particular climate in which it stands. Greenhouses: Advanced Technology for Protected Horticulture addresses the major environmental factors of light, temperature, water, nutrition, and carbon dioxide, and features extensive discussions of greenhouse types, construction, and climate control. The book highlights technology such as hydroponics, computer control of environments, and advanced mathematical procedures for environmental optimization. Greenhouses: Advanced Technology for Protected Horticulture is the definitive text/reference for the science of greenhouse engineering and management. The author Dr. Joe J. Hanan, Professor Emeritus of Colorado State University, is the recipient of the Society of American Florists' (SAF) 2000 (Millenium) Alex Laurie Award for Research and Education. The Alex Laurie Award is presented annually to an individual who has made broad-scope, long-lasting contributions to the floriculture industry through research or education. The award is named for Alex Laurie, a professor at The Ohio State University, who pioneered work in many areas of floriculture. "Joe is one of the most precise floricultural researchers I have known," said Dr. Gus De Hertogh, Chairman of SAF's Research Committee. "That excellence is reflected in his latest book, Greenhouses, Advanced Technology for Protected Horticulture, which was published in 1998, nine years after his official 'retirement.'"
Hydroponics, the method of growing plants without soil, presents a feasible alternative to conventional farming in areas which are short on water supply and limited in agricultural soil. This book will serve as an indispensable guide for students in the agriculture sciences, for agriculture instructors and soilless-culture farmers. It provides up-to-date information on optimal plant nutrition, deficiencies and toxicities of nutrients, plant growth media, optimal root environment, environmental control, carbon dioxide requirements, saline conditions and use of sewage in soilless culture. Other topics include economic aspects of hydroponics, new growth methods and an outlook for the future.
GRAFIS is a word processor specifically developed for disabled people at ICSFORTH in the framework of the HORIZO% ESTIA Project. This project ran from January 1996 to June 1998 and focused on the vocational training of unemployed disabled people, through the use of information technologies.
Tomato plants were grown in nutrient film (NFT) at constant salinities of 3, 5.5 and 8 mS cm−1 and also with the salinity fluctuating from 8 mS cm−1 during the day to 3 mS cm−1 at night (the 8/3 mS treatment). The yield was always depressed at 8 mS cm−1. During the first four weeks of harvesting this was mainly due to reduced fruit size, but later fruit number also decreased. The 8/3 mS treatment reduced fruit size and number more than a constant 5.5 mS cm−1 (the average of the fluctuating salinities), suggesting that 8 mS cm−1 affected the long-term development of the plants. Increasing the salinity by addition of either major nutrients (K, Mg, Ca and NO3–N) or NaCl gave similar responses. The sugar and acid contents of the fruit juices increased with salinity but these responses disappeared when the data were expressed on a dry matter basis. This lack of response to salinity was confirmed by the sugar analyses of fruit after freeze-drying. Increasing the salinity with NaCl depressed the K content of the dry matter but increased the Na content; both responses were greater with the 8/3 mS treatment than at a constant 5.5 mS cm−1. The depression in the Ca content of the fruit was more marked in the later trusses and in the distal tissues of the fruit. This decrease was more severe with the 8/3 mS treatment than with a constant 5.5 mS cm−1, thus supporting the notion of a long-term effect of salinity on xylem development. The fluctuating salinity did not, therefore, appear to have any advantage over a constant one.
Environmental concerns and economics require the recycling of plant nutrient solutions (PNS) used in soilless cultures in greenhouses. To avoid possible outbreaks of plant diseases, disinfection of the recycled PNS might be necessary. This paper describes a case study on the stability of Fe 3+- chelates, present in PNS and exposed to ultraviolet radiation (UV 254 nm) for disinfection, and the effect on plant growth. Three Fe-chelates, each containing 2 mg Fe 3+ l -1, in PNS were: i, Fe-EDDHA (Fe-ethylene-diamine- dihydroxyphenyl acetic acid); ii, Fe-Na-EDTA (Fe-ethylene-diamine-tetra- acetic acid); and iii, Fe-DTPA (Fe-diethylene-triamine-pentaacetic acid). Seedlings of sorghum, corn and tomatoes were grown hydroponically for four weeks in continuously aerated PNS, which had been exposed previously for 0, 2.5 and 130 s to a UV radiation fluence of 80 mW s -1 cm -2. The accumulation of plant fresh weight (APFW) differed from non-treated controls, depending on chelating agent and on exposure time to UV. The greatest APFW was observed in sorghum (128, 178 and 98%) at 2.5 s UV-exposure for PNS containing i, ii and iii, respectively. For corn and tomato, the respective results were: 108, 139 and 96%, and 129, 91 and 89% for tomatoes, respectively. The stability of i, ii and iii upon exposure to UV radiation is discussed.
This chapter discusses interface metaphors and the user interface design. The integration of operational, structural, and pragmatic approaches to metaphors can provide guidance and a starting point for the design of a user interface that integrates a central metaphor, with a carefully analyzed similarity basis and a set of planned mismatches, with myriad other interface elements that support and exploit the matches and mismatches inhering in the metaphor. Metaphoric comparisons and interface presentations do more than render static denotative correspondences. They have motivational and affective consequences for users. They interact with and frame users' problem-solving efforts in learning about the target domain. Metaphors have been employed to increase the initial familiarity of the target domain, but they have an inevitable further role to play. The ultimate problem that the user should solve is to develop an understanding of the target domain itself—a mental model. Interface metaphors should also be viewed as tools proffered to users for articulating mental models.
For fruit-vegetable crops it has been found that a raised electrical conductivity (EC) of the nutrient solution improves fruit quality. To test this effect for flower crops, an experiment was conducted with rose (Rosa hybrida) grown in rockwool in six treatments: EC-values ranging from 1.0 to 5.0dS.m−1 in the drip-irrigation water and from 1.1 to 7.1 dS.m−1 in the drainage water; the leaching fraction was 30-42%. Stem thickness, length and firmness, and vase life were negatively affected by a high EC. Optimum flower production was obtained at an EC of the irrigation water of 1.4 dS.m−1, corresponding to 2.4 dS.m−1 in the drainage water. Low EC gave a stronger reduction in summer than in winter, and an EC higher than the optimum gave the severest reduction in winter. Nutrient uptake, based on the mineral composition of the plant, relative to water uptake was, in mM: N5.8, P0.4, K2.0, Mg0.3 and Ca 0.7. With the leachate a considerable amount of the nutrients was lost.