Polytechnic University of Tirana

In this paper, we are presenting a numerical investigation of Duffing’s nonlinear system. The Duffing’s system is described by a nonlinear second-order differential equation, which shares he same structure like the damped and driven oscillator systems. The numerical integration of the system is done using Python scientific libraries such as NumPy and SciPy. The proposed technique is utilized to construct the bifurcation diagram and the Poincaré section and to analyze the behavior of the system by changing one parameter. This proposed method is characterized by versatility and the extrapolation of these numerical techniques and algorithms in the study of other nonlinear dynamical systems.

This paper presents a simulation study for a semiconductor laser with optical feedback based on the Lang-Kobayashi model. The analysis of the system’s dynamical behavior, utilized using Vicente equations, has provided evidence of the presence of chaotic behavior. Performing detailed numerical simulations, we have explored the parameters, revealing the transitions of the system from stable operation to chaotic. Our findings corroborate previous theoretical predictions and offer new insights into the complex behavior of semiconductor lasers under feedback conditions. The results have significant implications for applications where controlled chaotic behavior is desirable, such as secure communications and random number generation.

Applications have rapidly transformed the data access, business operations, and communication methods. This sudden shift has resulted in significant security challenges such as Distributed Denial of Service (DDoS) attacks, which intensify Internet security issues. This paper introduces a novel approach to enhancing the Web Application Firewall (WAF) for detecting and mitigating botnet-based DDoS attacks through the use of Machine Learning (ML) and blockchain technologies. Legacy security systems often struggle to adapt to evolving digital threats, particularly with the rise of complex botnet designs. The integration of ML and blockchain within the WAF ecosystem represents a substantial advancement in cyber defense mechanisms. Insights are provided into the development of advanced ML algorithms for precise anomaly detection and the formulation of efficient blockchain protocols for streamlined threat intelligence sharing.

This work reports for the first time, the experimental densities and sound speeds for the ternary system {methyl tert-butyl ether + benzene + cyclohexane} within the temperature range (293.15 to 313.15) K and under ambient pressure conditions. The related binary subsystems have also been reported. Experimental data were used to derive excess molar volumes and excess isentropic compressibilities. Redlich-Kister and Cibulka’s equations correlated the binary and ternary excess properties, respectively, with standard deviations falling below the estimated uncertainties of the corresponding properties. The results have been interpreted in terms of molecular interactions between mixtures’ components and structural effects. Additionally, two symmetric (Kohler and Muggianu) and two asymmetric (Hillert and Toop) binary contribution models have been tested for their ability to predict the excess properties of the ternary excess properties.

Experimental densities at temperatures (293.15, 298.15, 303.15, 313.15, 323.15, and 333.15) K and under ambient pressure conditions are reported for the first time for the ternary system (butan-1-ol + cyclohexane + benzene) covering the entire composition range. The corresponding binary subsystems (butan-1-ol + cyclohexane), (butan-1-ol + benzene), and (cyclohexane + benzene) have also been studied. The excess molar volumes, derived from experimental densities, were calculated and correlated by using Redlich–Kister and Cibulka equations for binary and ternary systems, respectively. Results have been discussed in terms of molecular interactions between the mixture’s components and structural effects. The Jouyban-Acree model was used to represent the composition and temperature dependence of the densities of the studied binary and ternary mixtures. The accuracy of the Jouyban-Acree model was evaluated, and the absolute average percentage deviation between experimental and correlated densities was less than 0.06 and 0.08% for binary and ternary mixtures, respectively. Further, the ternary excess molar volumes are compared with the predicted values from binary contribution symmetric (Kohler and Muggianu) and asymmetric (Hillert and Toop) models. The asymmetric models outperformed the symmetric ones when butan-1-ol was chosen as the asymmetric component.

“Defensive Architecture of the Mediterranean” (volumes XVI and XVII) is the continuation of a series of publications that highlight the latest research on the fortifications of the Mediterranean region. These contributions were gathered in the seventh edition of the international conference Fortifications of the Mediterranean Coast, FORTMED 2024, hosted by Universiteti Politeknik i Tiranës in Tirana, Albania on April 18, 19, and 20, 2024.The series 'Defensive Architecture of the Mediterranean' aims to share knowledge about the historical and current state of military architecture along the Mediterranean coast, including structures built overseas that are influenced by those in the Mediterranean.The conference and the 17 published volumes of the series have demonstrated to be the most persistent and serious effort in researching and documenting military architecture in the Mediterranean over the last decade.While fortresses and castles have always been recognized as vital components of historic built heritage, their strategic defensive role hasn't always been fully understood and explored. The study of military architecture, a multidisciplinary task, prompts a reassessment of this cultural environment, often neglected or at risk. From prehistoric fortification traces to contemporary bunkers and military infrastructures, the discourse on documenting and preserving military heritage welcomes and encourages contributions from diverse fields, including architecture, engineering, archaeology, history, geography, and cultural heritage.FORTMED, the international conference on the Fortifications of the Mediterranean Coast, has evolved into a research-based platform that transcends borders and centuries, delving into the strategic, historical, and cultural significance of fortifications along the Mediterranean coast. FORTMED has embraced diverse venues, ranging from Valencia to Florence, Alicante to Turin, and later to Granada, and finally to Pisa. These conferences have become synonymous with collaboration, knowledge exchange, and the exploration of multifaceted perspectives on defensive architecture. This initiative has turned into an intellectual odyssey, traversing the historical landscapes of the Mediterranean, exploring intricate fortifications that have shaped civilizations, and engaging with contemporary challenges in the preservation and restoration of architectural heritage.

Magnetic micro and nano sensors can be used in a broad variety of applications, e.g., for navigation, automotives, smartphones and also for health monitoring. Based on physical effects such as the well-known magnetic induction, the Hall effect, tunnel magnetoresistance and giant magne-toresistance, they can be used to measure positions, flow, pressure and other physical properties. In biomedicine and healthcare, these miniaturized sensors can be either integrated into garments and other wearables, be directed through the body by passive capsules or active micro-robots or be implanted, which usually necessitates bio-functionalization and avoiding cell-toxic materials. This review describes the physical effects that can be applied in these sensors and discusses the most recent micro and nano sensors developed for healthcare applications.

Vertical shortening, a phenomenon inherent to concrete structures, plays a key role in the quality and safety of construction, particularly in tall reinforced concrete buildings. This behavior is intrinsically linked to the time-dependent properties of concrete, encompassing both creep and shrinkage. Neglecting these aspects, especially when non-uniformly distributed, can give rise to various structural issues, including partition distress, overloading, and potential cracking in horizontal elements. This paper delves into the principal factors influencing vertical shortening and presents a rigorous approach to their evaluation, treating creep and shrinkage as critical parameters. The investigation employs two illustrative case studies: the first revolves around a 15-story reinforced concrete building with single columns supporting tributary areas at various levels, acting as a calibration case; the second encompasses a 30-story reinforced concrete structure employing a dual system, providing a broader perspective applicable to three-dimensional structures. A diverse array of analyses is conducted, incorporating considerations for concrete's linear and nonlinear behavior as well as the impact of construction stages. Our findings reveal that vertical shortening is directly proportional to the building's height and inversely related to concrete strength, longitudinal reinforcement ratios, member dimensions, volume-to-surface ratios, age of the structure upon load application, and relative humidity. Consequently, precise assessments of differential shortening effects are paramount. The utilization of staged construction analysis and time-dependent effects is recommended as the most suitable approach for evaluating vertical shortening effects.

The activities of marketing new vehicles and the enterprises that service and repair them, have as their primary purpose the increase of sales and financial income. In the conditions of ever-increasing competition for these types of activities, the “quality” component of the services offered takes on a special importance. The rapid spread of these types of services in our country definitely requires that it be accompanied by new methodological approaches, in order to be successfully integrated into the modern economy of Europe. In this aspect, the vehicle service market in general considered as the relationship between the subjects “vehicle owners” and “service companies”, which is guided by the universal demand-offer relationship, has the sole purpose of maintaining the ability to work or the efficiency of vehicles during the entire life-time period of service. The purpose of this article is to promote the use of innovative management technologies of enterprises that serve the means of transport, such as the 5S System Methodology.

The aim of this article is to approve a procedure for the integrity evaluation of a concrete structure based on the low frequency ultrasonic tomography that is the new method in concrete evaluation technology. The procedure was built and performed in the NDE integrity of the CLINCER 40,000 ton concrete located in north Albania. The procedure of the NDE integrity is write as a combination of the visual inspection performed for more than 30%, of the outside surface, rebound hammer technic and the low frequency ultrasonic tomography techniques. The visual inspection locates sign of corrosion, deterioration, mechanical damage on the surface determining the typology and size. Rebound hammer technic of the compressive strength of the concrete give data to determine the quality of concrete according European standards. In the areas where the discontinuities are indicated and the evaluation of the concrete quality is performed, the volume of the wall was scanned with low frequency ultrasonic tomography system, that provides good penetration depth, good sensitivity and imaging resolution by implementing three dimensional image. The equipment used is low frequency ultrasonic tomography ACS A1020 MIRA Lite. After all the inspection results of the procedure proposed was satisfactory, regarding reinforcement bars localization, detection of voids, estimation of their position, and thickness measurements from one side. Those elements are the foundations of the NDE integrity of the concrete structure.

ML (Machine Learning) is frequently used in health systems to alert physicians in real time. This helps to take preventive measures, such as predicting a future heart attack. This study presents ML combined with various forms of feature selection to identify heart disease. It includes the analysis of different algorithms such as Decision Tree, Logistic Regression, Support Vector Machine, Random Forest and hybrid models. This results in SVM and RM performing better after applying feature selection for individual ML models. Meanwhile, hybrid cases provide good results if the ensemble is done using a Voting Classifier. Our approach in this paper is based on our study of existing literature and methodologies. We can conclude that, for the used dataset, the Voting Classifier appears to be the most accurate and precise model out of all individual and hybrid classifiers that use feature selection techniques.

The ultra-deep genesis of ophiolitic peridotite has reshaped our perception of the genesis of the oceanic mantle. Although ultra-high pressure (UHP) mineral assemblages have been unearthed in dozens of ophiolites in different orogenic belts around the world, the vast majority of them have been limited to podiform chromitites formed in suprasubduction zone (SSZ) settings, leaving uncertainty about whether such UHP minerals are intrinsic to the oceanic mantle or influenced by a specific mantle rock type. Here, we report on the occurrence of diamonds recovered from the harzburgites within the Skenderbeu massif, Mirdita ophiolite. The whole-rock, mineralogical major and trace element compositions, and redox states of the harzburgites align with modern abyssal harzburgites. Trace element modeling of clinopyroxene indicates that harzburgites have endured varying degrees of garnet-facies melting (~2%–5%) before progressing to spinel-facies melting (~10%–12%). Mineralogical characteristics further support that the Skenderbeu harzburgites underwent late-period MORB-like melt metasomatism in a forearc spreading center. An unusual mineral assemblage of diamonds has been separated from the studied harzburgites. The first occurrence of ophiolite-hosted diamonds discovered in the forearc harzburgites, together with previous similar discoveries in the SSZ ophiolitic chromitites, suggest that the ophiolite-hosted diamonds are not specific to certain mantle rocks.

Vjosa is the main river of South Albania. Currently, the confined Quaternary gravelly aquifer in its lower course supplies drinking water for roughly 300,000 local residents. In the past years, extracted groundwater quantity has increased, whereas the groundwater quality has been affected by seawater intrusion. This paper aims to assess the groundwater quality and to discuss the dominant hydrochemical processes in the aquifer. To fulfil this goal, the study discusses the groundwater quality’s spatial and temporal variations on the basis of the hydrochemical parameters and ratios for 2010–2021 period, during which data are collected from three monitoring wells, located 6, 14 and 17 km, from the sea. While for 1961–2009 period, hydro-chemical water types and TDS maps are prepared using roughly 100 chemical analyses. The hydro-chemical parameters are discussed related to the factors controlling the groundwater’s chemical constituents and the groundwater extraction. Heavy metals and nitrates’ contents indicate that the aquifer is not affected by anthropogenic pollution. The main conclusion is that the groundwater quality is affected by seawater intrusion due to overexploitation. The study reveals its gaps, mentions its possible usefulness, and underlines the discrepancy between the policy makers and the hydrogeologists approaches concerning groundwater extraction.

Influence lines are indispensable tools for visualizing and analyzing the dynamic variations in force factors induced by external loads within structural systems. Among these methods, the energetic approach stands as a widely employed technique, rooted in the fundamental principle of work done by changing forces. It enables engineers to transform intricate structural analysis problems into manageable ones by exploring the first derivatives of the radius vector, which represent infinitesimal velocity or displacement. This methodology seamlessly interweaves concepts such as carrier motion, relative motion, and the construction of mechanisms, bringing fresh perspectives to the analysis of influence lines. In this article, we explore the nuances of these novel methods within the domain of mechanism theory. Through comprehensive elaboration and analysis, we elucidate the underlying principles and practical applications of Jacobian contours. Crucially, we introduce a straightforward, rapid, and programmable approach, promising to revolutionize influence line determination in structural engineering. This method bridges the gap between theory and practice, offering the potential to elevate the accuracy, efficiency, and adaptability of influence line analysis. As such, it represents a significant advancement in the field of structural and applied mechanics, with broad-reaching implications for engineering practice.

Geothermal energy sources in Albania are estimated as warm water sources of the underground layers of the earth, which have a sufficient temperature to be used as a source of energy. The area of Elbasan is a special area because it has a significant number of sources with geothermal potential. This area, as part of the Kruja geothermal area, has a length of 180 km and a width of 4-5 km. The current average flow of thermal water is about 15-18 l/s and temperatures vary from 55-65oC. It is estimated that the resources have specific reserves of 39.6 GJ/m2 and potential power to install 2760 kW. It is about thermal sources with low enthalpy and maximum temperature up to 80oC. The emergence of hot water on the surface shows that these thermal springs are mainly located near the result of intense tectonic activity in the seismically active parts. The geothermal regime of the geological structures in the area of Elbasan is conditioned by the heat flow density, the geothermal gradient and the distribution of the temperature field at different depths of these sources, closely related to the lithology of the geological structures, as well as to the hydrodynamics of underground waters.

Albania is part of one of the most active seismic regions in Europe with dozens of devastating earthquakes throughout history. In this study, we will present an investigation of the earthquakes of the Elbasani region, in terms of the location accuracy and analysis of the features of the seismoactive layers. The distribution of focal depth shows the activation of a lithospheric zone, which extends in depth between 0 and 40 km. Accurate assessment of seismoactive layers of the Elbasani zone is of great interest in the recognition of the real depth of seismic energy generation and relations with low velocity layers. The depth of earthquakes has particular interest in the case of moderate and strong earthquakes because it is related to their effect on the surface. Strong earthquakes with shallow focal depth cause greater damage than earthquakes of the same magnitude but with a deeper focal depth. The b-value depth analysis is related to the stresses for the seismoactive layers. The crustal structure of the Elbasani zone with high b-values is likely to be associated with crustal low-velocity zones. The earthquakes are relatively smaller beneath the low-velocity zones where the high heat flow values are observed. The location of moderate earthquakes with depths from 20 to 35 km, which means less surface effect than the same earthquake with a depth smaller than 10km. The intensity in the epicenter is dependent by the magnitude and by the focal depth. Analysis of these earthquakes show that shocks with Ml > 4.5 have greater depths than earthquakes with smaller magnitudes. This analysis shows that the seismoactive layer in Elbasani zone lies at a depth of about 30 km. These results are a step towards more detailed geodynamic and seismotectonic analysis.

The purpose of this study is the analysis of the dynamics of tectonic movements accompanied by two strong seismic events that occurred in the Durres area (Albania) in September-November 2019, through the use of GNSS technology, applied to national permanent satellite geodetic networks. Previous studies have been carried out on our study area by foreign authors from Croatia, Greece, and Italy. For our study case, we relied on geodetic weekly data secured from the Bulletins of Italian and Austrian stations, BSW52, of some of the constituent points of the two national permanent satellite networks of Italy (5 points) and Albania (6 points), located on both sides of the dividing line between the Eurasian tectonic plate and the Adriatic microplate. The analysis of the data secured in 7 campaigns was carried out by grouping them into 3 main analysis periods: the period before the September earthquake (F1-F4, called A), the period during the earthquakes (F4-F5, called B), and the period after the November earthquake (F5-F7, called C). It turns out that in plan the speed of movement in the area is: -0.00294m/year for period (A), -0.01912m/year for period (B), and -0.00305m/year for period (C). While in height, the speeds of movement are: 0.00130m/year for period (A), -0.04268m/year for period (B), and 0.00273m/year for period (C). These vectors also show us that the intensity T between period (B) and the average periods (A, C) is about 17 times in plan and 42 times in height. Combined this analysis with data that includes strong consecutive seismic events in the area, we believe that this intensity T can lead us to the most accurate predictability of the moment of the occurrence of the next tectonic energy release, thus of the next earthquake.

Experimental densities ρ and sound speeds u at temperatures (293.15, 298.15, 303.15, 313.15, 323.15, and 333.15) K and under ambient pressure are reported for the first time for the ternary system (2-methylpropan-1-ol + cyclohexane + benzene) covering the entire composition ranges. The corresponding binary subsystems (2-methylpropan-1-ol + cyclohexane), (2-methylpropan-1-ol + benzene), and (cyclohexane + benzene) have also been studied. The experimental data were used to derive excess thermodynamic properties, namely excess molar volumes VEm and excess isentropic compressibilities κES. The variation of VEm and κES with composition and temperature have been interpreted in terms of molecular interactions between the components of the mixture. The Redlich–Kister polynomial was used to correlate the excess thermodynamic properties of the studied binary mixtures. The Cibulka equation was the mathematical model of choice to correlate the ternary excess properties. Furthermore, the Jouyban–Acree model was used to mathematically represent the density and sound speed of the studied mixtures at different temperatures. The accuracy of the Jouban–Acree model was evaluated, and the absolute average deviation (APD) for density and sound speed of the binary mixtures was less than 0.07 % and 0.21 %, respectively. The APDs for density and sound speed of the ternary mixture were 0.30 % and 0.64 %, respectively.

In this paper, we are presenting a new pedagogical method for the introduction of the study of nonlinear systems. Our approach is based on the use of open-source software which is publicly available. In response to this motivation, we are using the Python programming language which offers a holistic approach to scientific research. We will present the analysis of the pendulum motion under the influence of an external force. The differential equation governing the system will be presented and solved using numerical methods. Moreover, the phase diagram of the system will be presented for various system parameters. We will describe the transition to a chaotic operation and the key factors of this procedure. The chaotic behaviour is verified by calculating the maximum Lyapunov exponent. This pedagogical approach emerging is based on the physical properties of the system and not on the numerical methods used so that the student can understand the dynamics of the system more comprehensively.