Christof Hübner

Mannheim University of Applied Sciences · Institute for Industrial Data Processing and Communication (IDK)

According to the Food and Agriculture Organization of the United Nations, climate change will negatively affect food security and increase pressure on freshwater resources [...]

Soil moisture profile sensors (SMPSs) have a high potential for climate-smart agriculture due to their easy handling and ability to perform simultaneous measurements at different depths. To date, an accurate and easy-to-use method for the evaluation of long SMPSs is not available. In this study, we developed laboratory and field experiments to eval...

Extreme weather phenomena are on the rise due to ongoing climate change. Therefore, the need for irrigation in agriculture will increase, although it is already the largest consumer of water, a valuable resource. Soil moisture sensors can help to use water efficiently and economically. For this reason, we have recently presented a novel soil moistu...

This paper describes a dataset of LoRa radio channel metrics, soil moisture and temperature measurements, weather and flux tower observations, from an underground sensor network on a farm site in Western Australia. The dataset comprises half hourly readings from 10 months of continuous monitoring over 10 radio channels (5 transmitters and 2 receive...

LoRa (Long Range) is a radio technology that facilitates low power communications over a large distance. The long range of communication means that a simple single hop transmission to a centralised gateway is sufficient for most applications. To supply this performance the LoRa physical layer offers a range of transmission parameters to tailor the...

The new far‐field low‐frequency electromagnetic method used the electromagnetic ground wave from distant radio transmitters at low frequencies to estimate temporal variations of factors affecting subsurface electrical conductivity averaged along the propagation path between either a transmitter and a receiver or two receivers that are in line with...

The level of automation in residential and commercial buildings has risen steadily over the years. This is not only due to the increasing demand for more comfort and convenience, but also the benefits building automation brings with regard to saving and managing energy.

Konnex (KNX), formerly known as the European Installation Bus (EIB), is a (industrial) building control communication system that uses information technology to connect devices such as sensors, actuators, controllers, operating terminals and monitors (see Fig. 3.1). KNX technology is designed to be used in electrical installations for implementing...

BACnet (Building Automation and Control Network) is a standardized data communication protocol developed by the American Society of Heating, Re-frigeration and Air-Conditioning Engineers (ASHRAE) for use in building automation to enable.

The performance of the LonWorks® technology has already been pointed out in Sect. 1.7.2.2. It is an open networking solution for building automation and control networks that was developed by the American company Echelon. It is designed in such a way that it can be used in centralized building automation controllers as well as in decentralized buil...

Industrial communication refers to the communication between industrial automation devices, as opposed to the use of language that we use to communicate with each other.

Heating and cooling of residential buildings consumes around ten percent of the world's energy. One approach for reducing these costs is to exploit the high thermal mass of sustainable building materials, for example rammed earth (RE), for intelligent solar passive design. However, there is a lack of scientific evidence about the thermal performanc...

Heating and cooling of residential buildings consumes around ten percent of the world's energy. One approach for reducing these costs is solar passive design using building materials with high thermal mass such as Rammed Earth (RE). Several studies have examined the performance of small RE structures or individual rooms within RE dwellings and have...

Cereals and legumes are invaluable resources, as they represent the raw materials of many foods and beverages. Cereals are also largely used as livestock feeds, thus indirectly influencing the quality of dairy products and meat. Because of their key role in human nutrition and well-being, the safety and quality of these agri-food materials are extr...

In this work, the performance of three time domain reflectometry (TDR) instruments (with different hardware architectures, specifications and costs) is comparatively assessed. The goal is to evaluate the performance of low-cost TDR instrumentation, in view of the development of a completely permanent TDR-based monitoring solution, wherein the costs...

Soil moisture is an important state variable in the terrestrial system because it controls the exchange of water and energy between the land surface and the atmosphere. In this study, we review recent advances in noninvasive techniques that allow continuous noninvasive and contactless measurements of soil moisture dynamics at the field to basin sca...

The cost of construction in remote areas of Australia is extremely high due to the need to transport materials, manpower and equipment over long distances. Due to its use of local materials and labour, rammed earth construction offers a potential solution to this problem. This paper introduces the design, construction and monitoring of two rammed e...

German collaborators Abstract—Spatial Time Domain Reflectometry (spatial TDR) is a measurement method for determining water content profiles along electrically insulated probes (transmission lines). The method is based on the inverse modeling of TDR reflectograms using an optimisation algorithm. By means of using flat ribbon cables as sensors it is...

Wireless sensor networks for environmental monitoring and agricultural applications often face Long-range requirements at low bit rates together with a large numbers of nodes. This paper presents the design and test of a novel wireless sensor network that combines a large radio range with very low power consumption and cost. Our asymmetric sensor n...

Time-domain reflectometry (TDR) is a well-known measurement principle for evaluating frequency-dependent electric and dielectric properties of various materials and substances. Although TDR is a proven method, the high price for TDR measurement equipment and complex laboratory setups is often a limiting factor for cost-sensitive applications or lar...

Against the background of climate change and decreasing water availability in many parts of the world, there is the need for soil moisture information to improve water efficiency in agricultural irrigation. This study presents a newly developed sensor, which measures simultaneously soil water content and correlated soil water potential. Water conte...

Due to the climate change and decreasing water availability in many parts of the world, water efficient irrigation becomes more and more important to stabilize or even increase agricultural productivity. An efficient irrigation scheduling relies on soil water potential information in order to define the optimal irrigation start as well as on soil w...

Compressing sensor data benefits sensor network applications because compression saves both transmission energy and storage space. This paper presents a novel lossless compression algorithm for sensor networks that is both data-aware and resource-aware. The DARA algorithm provides high compression ratios and also has a small memory footprint and ef...

Wireless sensor networks using transmit-only sensor nodes are a promising new approach for applications such as environmental monitoring because they can provide high network scalability and long life-time at low cost. But achieving reliable data delivery in a transmit-only network is a challenging problem because there is no feedback channel for r...

Against the background of climate change and decreasing water availability in many parts of the world, there is the need for soil moisture information to improve water efficiency in agricultural irrigation. This study presents a newly developed sensor, which measures simultaneously soil water content and correlated soil water potential. Water conte...

The IEEE 802.15.4 standard specifies the most recommended medium access control (MAC) protocol for Wireless Sensor Networks (WSNs). The contention-based access scheme of the MAC is driven by a Carrier Sense Multiple Access with Collision Avoidance (CSMA-CA) algorithm. In this paper, we evaluate the performance of the CSMA-CA algorithm for indoor WS...

Wireless sensor networks generate volumes of scientific observations. However, gathered data is typically not published for use by other scientists. This paper analyses the reasons that so little sensor network data is published online in a usable form, and identifies gaps in currently available publication systems. To address these gaps we present...

A new approach for obtaining integrated estimates of soil moisture content over larger regions of typically 10–50km is described. It is based on a known correlation between propagation characteristics of low frequency radio surface waves and surface soil moisture, and provides valuable new benefits especially for meteorological prognostic models an...

Wireless sensor networks for environmental monitoring and agricultural applications often face long-range requirements at low bit-rates together with large numbers of nodes. Most existing wireless sensor networks use nodes with a short-range radio and use software protocols to schedule the nodes and co-ordinate multi-hop routing in order to minimis...

The density is an important state variable for soils relevant for the evolution of geomechanical processes and geohydraulic properties. The central role of the density makes it necessary to quantitatively determine the phase contents and thus the porosity in laboratory and in field. A new approach to measure porosity distributions of saturated gran...

Based on a short introduction to the dielectric properties of water and aqueous solutions, this review summarizes current techniques of electromagnetic aquametry. The techniques described here include time-domain and frequency-domain procedures, enabling moisture determination in a broad spectral range from millihertz to terahertz frequencies. In t...

Dependable spatial-temporal soil parameter data is required for informed decision making in precision farming and hydrological applications. Wireless sensor networks are seen as a key technology to satisfy these demands. Hence, research and development focus is on reliable outdoor applications. This comprises sensor design improvement, more robust...

Time domain reflectometry (TDR) was used for the spatial observation of transient density changes in a laboratory shake-box apparatus. Shake-box experiments are conducted to investigate the liquefaction of soils due to seismic excitation. As a sensor, a flat ribbon cable was placed within a water saturated sand column two metres in height. In the e...

Many applications in geotechnical engineering require knowledge of total pressure distributions. So far, only measurements at single points at individual locations of interest can be carried out with conventional geotechnical measurement devices. Time-domain reflectometry (TDR) has already been used to assess the amount of shearing at multiple dist...

Spatial time domain reflectometry (spatial TDR) is a new measurement method for determining water content profiles along elongated probes (transmission lines). The method is based on the inverse modeling of TDR reflectograms using an optimization algorithm. By means of using flat ribbon cables it is possible to take two independent TDR measurements...

Konnex (KNX), formerly known as the European Installation Bus (EIB), is a (industrial) building control communication system that uses information technology to connect devices such as sensors, actuators, controllers, operating terminals and monitors (see Fig. 3.1). KNX technology is designed to be used in electrical installations for implementing...

Industrial communication refers to the communication between industrial automation devices, as opposed to the use of language that we use to communicate with each other. The devices in an automated system or process must be able to communicate with each other. This flow of information can be classified into levels using, for example, the three-tie...

LonWorks® is an open networking solution for building automation and control networks that was developed by the American company Echelon. It is designed in such a way that it can be used in centralized building automation controllers as well as in decentralized building control components. LonWorks is a standardized bus system (ANSI/CEA-709.1-B and...

The level of automation in residential and commercial buildings has risen steadily over the years. This is not only due to the increasing demand for more comfort and convenience, but also the benefits building automation brings with regard to saving and managing energy. Security is another important factor, particularly in residential buildings. Wh...

BACnet (Building Automation and Control Network) is a standardized data communication protocol developed by the American Society of Heating, Re-frigeration and Air-Conditi-oning Engineers (ASHRAE) for use in building automation to enable devices and systems to exchange information. BACnet is used in numerous building automation systems worldwide an...

Monitoring of transient soil moisture profiles yields valuable insight into soil hydraulic processes. A recently developed reconstruction algorithm allows deriving water content profiles along extended moisture probes from Time Domain Reflectometry (TDR) signals. Based on inverse modelling of the wave propagation along a transmission-line the algor...

Time Domain Reflectometry (TDR) is a widely-used tool for the point-wise determination of water contents in soils, especially in hydrology and soil-physics. Another well-known field of application of TDR is the observation of deformation processes in soils or rocks. The development of Spatial TDR offers new fruitful possibilities in geohydraulics a...

Time-domain reflectometry (TDR) is a well-known method for measuring moisture in materials. Standard waveform analysis only provides the average water content along the TDR sensor, while more sophisticated methods are required to resolve the spatial water content profile. A reconstruction algorithm has been developed which calculates water content...

The measurement of moisture distribution in bentonite gate structures is stringently necessary for the indefinable trend of fluid access and for long-term security analyses. A TDR moisture measurement system using flexible cable sensors has been applied. Finite element electromagnetic field simulation of both the sensor and the surrounding material...

Microwave moisture measurements refer to a methodology by which the water content of materials is non-invasively determined using electromagnetic fields of radio and microwave frequencies. Being the omnipresent liquid on our planet, water occurs as a component in most materials and often exercises a significant influence on their properties. Precis...

Time domain reflectometry (TDR) is a well-established method for the measurement of moisture in various materials, especially soils. Standard waveform analysis usually provides the average water content along the length of the TDR probe, while more sophisticated methods are required to reconstruct the spatial water content profile. A reconstruction...

The measurement of moisture distribution in bentonite barriers in salt mines is absolutely essential in order to monitor fluid ingress and record data for long-term security analyses. The aim of this investigation was to apply a TDR measurement system using flexible flat band cable sensors in the harsh environment of a salt mine. The measurement of...

A simple and cost-effective soil moisture probe is described. It consists of a transmission line in the feedback loop of a ring oscillator, which can be embedded in soil or other material of interest. The water content of the surrounding material influences the frequency of the oscillator counted by a microcontroller circuit and transformed into wa...

Surface barriers for waste disposal sites should prevent waste water and gas emission into the environment. It is necessary to assess their proper operation by monitoring the water regime of the containment. A set of three new water content measuring devices has been developed that provide an economical solution for monitoring the moisture distribu...

Spatial TDR is an advanced TDR technology which allows to measure soil moisture profiles at a high temporal and vertical resolution. This method consists of three components: a sampling TDR device, an appropriate moisture probe, and a reconstruction algorithm, with which a time-dependent voltage signal recorded by a sampling TDR can be transformed...

As part of the natural resource management (NRM) the exploitation and assessment of water resources from melted snow, the snow water equivalent (SWE) for hydro power generation can proceed only by remote sensing. The evaluation algorithm EQeau is already introduced for this assessment. This connects the remotely data to the SWE exploiting the seaso...

The knowledge of soil and snow water content is essential to many applications in me- teorology, agriculture, hydrology and civil engineering. Most of the measuring tech- niques known to date are unable, however, to meet the user requirements in terms of accuracy, spatial resolution and measurement volume. Therefore a new moisture sensor technology...

Many applications in hydrology, agriculture and civil engineering require the moisture profile in soils or building constructions. So far time domain reflectometry (TDR) technology as a well established moisture measurement technology has been limited to integral or very coarsely resolved water content determination along the transmission line. A n...

Mapping of subsurface contamination is one of the most important aims of environ–mental geophysics. For this purpose great efforts have been and will be carried out in the development of non-destructive geophysical mapping and monitoring techniques. In the growing field of different measurement devices the Ground-Penetrating RADAR (GPR) managed to...

The soil water content has a dominant influence on the dielectric permittivity E of porous media because of the high permittivity of water compared with the matrix. The well known Maxwell’s relation which is valid for most natural soils combines the permittivity and the phase velocity v of electromagnetic waves where co is the velocity of light in...

Measuring snow wetness and snow density is essential for many applications in snow hydrology like avalanche warning, flood prediction, optimization of hydro power generation and investigations of glacier melting due to global warming and climate change. So far the snow parameter sensors were not suited for long time continuous measurements when dis...

An attempt is started to define the terms of aquametry and its adjective subsurface. Subsurface Sensing represents a field of scientific research and development character, which is much wider than that of the classical non-destructive material testing in industrial production. It covers the 2 or 3D mapping of distributed parameters, broad applicat...

Subsurface sensing often implies the intention to look deep into the hidden structures. A special task is the analysis of the `skin' itself, which covers the deep structures and builds the surface layer which can not or may not be penetrated. There are also many cases where thin material layers are embedded in another materials and can be measured...

Waste disposals are covered with high density and highly saturated clay layers, which prevent rain penetration through waste into groundwater. These layers without monitoring are overdesigned to achieve long term performance. In case of a containment control, which means water content control, the construction can be less expensive and defects can...

Snow development characteristic and the liquid water content dynamic on glacier snow packs are very important parameters that may be monitored by radar. Accurate ground reference is required for the radar image calibration. The authors developed a new in-situ snow moisture and density measuring device. Measurements were made with this advanced devi...

At frequencies up to 1 GHz, the dielectric constant of water is approximately 80, compared to 3 to 5 for dry soils. Thus, electromagnetic measurement techniques can determine soil moisture on the basis of this large contrast. Three new sensors are presented, which improve the accuracy of existing measurement devices and extend the range of applicat...

The increase in accuracy of soil moisture retrieval from radar data requires a complete and accurate ground truth for calibration and verification. In order to support microwave backscattering models, one has to provide reliable permittivity and volumetric water content profiles of the soil. The conventional methods do not meet these requirements....

All remotely sensed soil moisture data have to be calibrated by reference measurements on ground. The gravimetric sampling (oven drying) is not suitable. It is time consuming, expensive, and destroys the site. Also the neutron probe has less and less acceptance. The remaining possibility is the dielectric moisture determination by rf or microwaves....

The increase in accuracy of soil moisture retrieval from radar data requires a complete and accurate ground truth for calibration and verification. In order to support microwave backscattering models, one has to provide reliable permittivity and volumetric water content profiles of the soil. The conventional methods do not meet these requirements....

Remedy selection of contaminated soil needs detailed information about water mobility on-site. Therefore the analysis of a suspected area has to be started with measurements concerning water mobility parameters as volumetric water content, porosity and bound water portion (earlier sorption).