bluuebunny/crossref_metadata_2025 huggingface dataset:
Possibilities of achieving the nZEB building standard (nearly zero energy building) and the passive building standard for newly designed buildings in Poland
Authors: Fedorczak-Cisak Małgorzata , Furtak Marcin , Surówka Maciej
Published: December 2020

For some time, a trend has been noticeable in the construction sector to reduce energy consumption. It is manifested by the tightening regulations of thermal protection of buildings, an increasing number of low-energy and even passive buildings, new technologies available on the construction market, or the new name of the “nearly zero energy” (NZEB) building standard. It is true that the definition of NZEB buildings appeared already ten years ago in the Energy Performance Directive No. 2010/31 / EU, but despite the fact that to some extent this type of buildings should already be the standard of construction, very few people know what is meant by NZEB and how it differs from the passive standard. The nZEB standard for newly designed buildings applies from January 1, 2021, to all European countries. Parameters for nZEB buildings are determined individually by each European country. In Poland, the requirements specifying the standard for nearly zero-energy buildings are included in the Technical and Construction Conditions. These requirements are very difficult to meet. The requirements apply to the thermal insulation of the external casing of buildings. This can be achieved by using appropriate materials and construction technologies, as well as by minimizing thermal bridges. The second requirement for nZEB buildings in Polish regulations concerns the Primary Energy indicator. This requirement can only be achieved through the use of appropriate energy sources, a very large extent Renewable Energy Sources. The article presents the possibilities of achieving the standard of newly designed buildings with “almost zero energy consumption” thanks to the use of appropriate materials, technologies, installations as well as heat and cold sources. The article also describes the standard of passive buildings, as well as the standard of passive buildings, which has been compared with the Polish standard of buildings “nearly zero energy building” (NZEB).
Thermomodernization of a Residential Building to NZEB Level
Authors: Kozak-Jagieła Ewa , Kusak Grzegorz , Klich Agnieszka , Mojkowska-Gawełczyk Małgorzata
Published: December 2020

Directive (EU) 2018/844 of the European Parliament and of the Council of 30 May 2018 amending Directive 2010/31/EU on the energy performance of buildings and Directive 2012/27/EU on energy efficiency introduces a zero-energy building standard, for which the energy balance per year is zero, i.e. the amount of energy obtained from renewable sources is equal to the annual demand. Each Member State shall establish a long-term renovation strategy to support the renovation of the national stock of residential and non-residential buildings, both public and private, into a highly energy efficient and decarbonised building stock by 2050, facilitating the cost-effective transformation of existing buildings into nearly zero-energy buildings. To achieve energy consumption at an appropriately low level in an existing building, you must adjust the heat transfer coefficients of the building envelope and the demand for primary energy to the requirements of the Technical Conditions for year 2021. Renewable energy sources, primarily from the sun, will also play a key role. A computational example of a single-family building shows which partitions are best modernized, what thickness of thermal insulation materials should be used to properly reduce heat transfer coefficients, and which installation systems to use to reduce the potential energy index (EP). It is also depicted as to how much the demand for usable energy in the building will decrease. This article aims to show residents of single-family buildings what steps should be taken to reduce energy consumption and thus - operating costs in an existing building to a minimum.
Protection Status of a World Cultural Heritage Site Under Tourism Development: Case Study of Shuhe Ancient Town
Authors: Li Bing , Xing Zhenpeng , Miao Li
Published: December 2020

In 2019, China joined Italy as the two countries with the most UNESCO World Heritage Sites. Among the Chinese heritage sites, the inhabited ancient towns, called Living Heritage, are the most difficult to protect in the eyes of many scholars. Only two Chinese ancient towns are listed as UNESCO World Heritage Sites, including the Old Town of Lijiang in Yunnan province, the most important settlement of the Naxi people. This indicates Lijiang’s significance in the protection of China’s cultural heritage. As one of three heritage sites within Lijiang Old Town itself, Shuhe is a pilot site for tourist development and heritage protection, led by the local government. In contrast to the Model of Dayan, the largest area and the earliest tourist development heritage site in Lijiang Old Town, Shuhe was renovated and modernised by a real estate company under the official guidance of the Lijiang government. This model was created to solve the contradiction between local development and cultural heritage protection in Shuhe. Since its renovation 17 years ago, the model of Shuhe has typical Chinese characteristics and has been a great influence on many other historical cities in China. After nearly 20 years of follow-up research, this study combs the development history of Shuhe Ancient Town, by analysing examples of architectural heritage transformation, and further reflects on the root causes of Shuhe development from the perspective of laws and regulations. The rapid development of tourism has become means for the local government and the people to lift themselves out of poverty at the cost of their historical heritage. The development of tourism has brought immediate economic benefits to the local government, developers, outside operators and local habitants in Lijiang. However, the original Naxi habitants have left their historic settlement, and the profound changes to the Naxi living environment have caused the Shuhe world heritage site to lose its original significance. In the renovation of heritage buildings, architects and craftsmen are not responsible for the modification of the historical heritage but are only tools for local governments, developers and outsider operators to gain wealth. The defects, backwardness and inability to fully implement the laws and regulations on heritage protection are the fundamental causes of Shuhe’s problems, which reflect the huge gap between the administrators’ awareness of heritage protection and the requirements of the professional guidelines of the UNESCO for the world cultural heritage protection.
Safety of Oil/Gas Offshore Platforms Designed According to European Provisions under the Action of Pulse-Like Ground Motions
Authors: Konstandakopoulou Foteini , Pnevmatikos Nikos , Papagiannopoulos George , Hatzigeorgiou George
Published: December 2020

Oil and gas offshore platforms are important civil constructions, which are loaded by various types of environmental actions such as wave loads and wind forces. These actions usually govern the platforms’ structural design, while seismic action appears to have minor influence. Nonetheless, numerous offshore structures have been founded in earthquake-prone regions where the structural design can be strongly affected by earthquake action. Many studies have investigated the seismic behaviour of oil and gas offshore platforms examining traditional seismic records. This study investigates the application of simple pulses, i.e., exponential, triangular, rectangular and sinusoidal pulse waveforms, as an earthquake excitation for offshore platforms. To the best of the authors’ knowledge, this is the first time that the aforementioned set of simplified ground motions have been applied to assess the nonlinear seismic behaviour of offshore oil/gas platform. It should be mentioned that pulses could make important information concerning the dynamic response available considering that many intense seismic events enclose actually an acceleration pulse, which can lead to a nonlinear structural response. It is worth noticing that a small number of works have examined the nonlinear response of the platform and most of the previous works assumed fixed boundary conditions ignoring the soil-structure interaction. On the contrary, this study investigates the structural response of 3-D platforms under the action of simplified pulses, considering also the soil-pile-platform interaction. It should be mentioned that the structural design of these special structures fulfils the Eurocode 8 standards. Finally, this work investigates the effect of angle of earthquake waves incidence.
Optimizing of the Geometrical Accuracy of Windows and External Doors
Authors: Veselá Linda
Published: December 2020

Geometric accuracy of building structures is an important part of the quality of construction work. Within the technical standards, it is assumed that the designer determines the functional geometrical parameters of building structures by calculation. The functional geometrical parameters are to be determined primarily for critical elements, i.e. for structures whose geometrical accuracy is important for structures that require high precision or are subject to functional requirements. If, for any reason, the designer fails to perform the calculation of the functional geometric parameters, the designer may use the recommended values of the geometric parameters given by the technical standards. The assumption is that the designers incorporate these geometrical deviations in the planning of spatial parameters of building structures, which should ensure that the minimum dimensional requirements for finished structures are met. The problem may arise in the implementation phase when the contractors follow the technical standards for the execution of individual parts of building structures. At present, when we adopt European technical standards, the system of technical standards is not interrelated and there may be situations where the standard requirements for the geometric accuracy of successive structures will differ significantly or will not be determined at all. These differences could lead to the fact, that the designer considered the design documentation with a margin for geometrical deviations for finished structures, with specified geometric accuracy requirements and required dimensions will not be met. One of these constructions are windows and external doors. Therefore, it is necessary to pay attention to the determination of the basic geometric accuracy requirements and to define procedures for the fulfilment of these basic requirements in all related operations.
Modeling of temperature distribution of engineering objects on the basis of data obtained from a thermal imaging camera and geodetic instruments
Authors: Kujawa Paulina , Muszyński Zbigniew
Published: December 2020

In the modern world, collections of various types of data have become the most valuable commodity. Data is obtained automatically or manually and comes from various measuring techniques, monitoring systems, sensors or methods of tracking human activity on the Internet. This combined with the idea of intelligent devices, which can automatically exchange data (Internet of Things), creates unimaginably large sets of data that seem to be unrelated to each other. Only the application of advanced Big data analysis can detect connections that are not visible at first glance. A common desire to integrate various types of measurement data also applies to engineering facilities. In the case of modeling temperature distribution, the integration of data from terrestrial laser scanning and thermovision, i.e. mapping of thermal images on point clouds, is very popular. This provides a three-dimensional representation of the tested object enriched with information about temperature. These types of models are used to identify damaged parts of the object, determine the size of leaks (e.g. heat and/or air leaks) or perform thermal analyses. In the classic approach, modeling of temperature distribution is performed in two-dimensional space using a set of quasi-continuous thermographic images with a colored scale or a set of point data with temperature values measured at a specific time. In the latter case, we can talk about the integration of spatial data (regarding the location of points, obtained by geodetic techniques) with the results of point measurements of temperature made by physical techniques (e.g. contactless pyrometer). The combined data sets can be further analyzed, e.g. using geostatistical methods, enabling continuous temperature distribution model to be obtained. This article presents the three-dimensional integration of data from two measurement techniques and methods to model the temperature distribution in two-dimensional space. Three-dimensional spatial integration concerned the point cloud acquired by terrestrial laser scanning and thermal imaging. The measurement object was a fragment of the ventilation system in the underground car park. Modeling of temperature distribution in two-dimensional space uses an unusual data source, which are temperature readings from a precision level, obtained during measurements of vertical displacements of a multi-level underground parking structure. These data, combined with images from a thermal imaging camera, enabled performing thematic maps of temperature distribution to be made using the IDW method and ordinary kriging. These maps can help in the future to interpret the values of vertical displacements of the parking structure.
Smart Solar Micro-exchangers for Sustainable Mobility of University Camps
Authors: Rosa-Jiménez Carlos , De-La-Bandera Isabel , Mora-López Llanos , Sidrach-De-Cardona Mariano , Álvarez-Gil Antonio , Camacho-Mérida Lourdes , Casauco-Tenllado Inmaculada , Delgado-Fernández Samuel , García-Moreno Alberto E. , Márquez-Ballesteros Maria J. , Ruiz Jessica Mendoza , Morales-Martín Alejandro , Nebot Nuria , Baena-González Jose Carlos , Ventura-Blanch Ferrán , Vías-Martínez Jesús
Published: December 2020

A significant number of universities have several campuses located in urban or rural settings, or with scattered university buildings that require the use of means of transportation. This implies the mobility and potential displacement of a large community of students, professors and researchers. The use of electric bicycles (e-bikes) is an intermediate alternative between the bicycle and electric cars. It can be an important stimulus for the promotion of the decarbonisation of the University Campus, avoiding the traffic congestion and reducing space requirements for parking. This paper presents the smart solar micro-exchanger model managed through a sustainable mobility web platform, applied to the case study of the University of Malaga (Spain). It is a solar charging station for e-bike, whose design is based on the principles of solar architecture (providing great security to e-bike). It managed by a web platform and app that allows the user to make reservations and learn about the savings in CO2 emissions. The system allows performing an aerobic sports activity without sweating problems when you reach the job. The platform also incorporates a database of quiet and safe routes for e-bike users.
Economic and Environmental Assessment of New Generation Concretes
Authors: Wałach Daniel
Published: December 2020

The identification of an anthropogenic environmental degradation has led to a transformation of social and economic trends in the world, which has resulted in the idea of sustainable development, which, in recent years, has become a key point of scientific consideration and a challenge for economic operators. Previously, the dominant aspects of the design of buildings and constructions were functional and structural issues. Nevertheless, based on sustainable development, a new approach to design has emerged, taking into account all the requirements for sustainable construction in one design process, called ILCD - integrated life-cycle design. The new concept combines the design of a building at the level of material, structural element and the whole structure, while, at the same time, assessing design solutions in terms of meeting technical requirements and, among others, economic and environmental efficiency. The development of concrete technology involving a new generation concrete with significantly improved properties, not only in terms of strength and durability but also in terms of rheology, has made it necessary to evaluate these materials from an economic and environmental point of view. The article presents such an assessment of new generation concretes. In this way, the idea of integrated design was presented in practice. The paper also indicates the sources of data and the tools that can be used for the inventory of the indicators for individual processes. The conducted analyses were also an attempt to estimate selected issues of the integrated design of new generation concrete technology against the background of normal concrete technology.
A City Game: Guidelines and Recommendations for Contemporary Urban Policy
Authors: Mazur-Belzyt Katarzyna
Published: December 2020

Cities are settlement units with a very diverse genesis and character. However, most of them are affected by similar, degrading social, economic and spatial phenomena. Solving city problems requires special attention and a very individual approach when looking for alternative functions, development opportunities and ways to improve the quality of life of their residents. The changes that constantly occur in the structure of the settlement network, as well as changing visions of shaping cities and problems related to such phenomena as: shrinking of cities, depopulation, suburbanization, metropolisation, climate change, etc. cause the need to answer the questions: what is the contemporary city vision and what contemporary urban policy should be in this connection. In order to solve the problems constructed in this way, several research methods and techniques were used. Among other things, a query was made of selected urban strategic documents and an analysis of the literature on the subject. On this basis, the vision of a modern city was determined. In the next stage of work, a proposal was prepared of a set of desirable directions of urban development and actions necessary for local government units to undertake in the area of spatial planning and development. These activities should support the qualitative and sustainable development of cities. This is the answer to social, environmental and economic needs. Nowadays, it is essential for improving the quality of life and planning for the benefit of future generations. Referring to the developed vision of the city, the author of the article presented recommendations that were divided into topics: compact and sustainable city, strong, efficiently managed, coherent, competitive, attractive and creative. An important element of contemporary urban policy seems to be the exchange of experiences between cities, promotion of examples of good practices and still underestimated social participation.
Behaviour of High-Modulus Asphalt Concrete from the Perspective of Deformation Characteristics - Stiffness
Authors: Valentin Jan , Kotoušová Adriana , Belhaj Majda , He Liang
Published: December 2020

High-modulus asphalt concrete is a specific type of asphalt mixture which is used for several decades in pavement engineering. It was originally invented as a solution which should help to minimize the effects of permanent deformation caused mainly by heavy traffic and mainly during the periods with elevated temperatures. These mixtures are used either in binder or base courses, whereas for base courses, it is important to combine reasonably the high stiffness with good fatigue life to avoid premature pavement failures not caused by rutting but by fatigue cracking. In this respect, various types of HMAC used and designed in the Czech Republic were tested first and foremost to determine stiffness. The stiffness modules were tested according to EN 12607-26, test method IT-CY, at selected temperatures representing cold, moderate and high service temperatures. The susceptibility to temperature change can be shown by thermal susceptibility for each mixture. In the parallel test, specimens were laboratory age to identify the changes in stiffness caused by thermo-oxidative ageing. This allows calculating a simple measure of the ageing index. Not presented in this paper but performed as a very last test was resistance to crack propagation.
Analysis of a Damaged Bridge Object as a Result of Vehicle Impact
Authors: Śliwka Andrzej
Published: December 2020

The article presents a case of damage to an object caused by an impact of vehicle or load. The bridge over the expressway has a typical structure used in Poland in the 70’s and 80’s of the last century. Spans were made of Płońsk beams (T beams) joined only by locks at the junction of the upper beams’ flanges. As a result of impact with the vehicle / load, there was a horizontal crack at the contact of the web with the top flange almost along the entire length of the beam. Visible stirrup deformation indicates complete loss of cooperation between beam elements at the point of impact. The part of strands were also broken. The method of estimating the load capacity of a damaged beam is discussed and the temporary protection of a damaged beam and recommendations for further handling of the bridge are presented.
Building-Integrated Photovoltaics from Products to System Integration – A Critical Review
Authors: Fedorova Anna , Hrynyszyn Bozena Dorota , Jelle Bjørn Petter
Published: December 2020

This review brings together research on the integration aspect of photovoltaic technologies in the building sector. Buildings are among the significant contributors of negative, yet not avoidable, environmental impact. Two primary drivers are pushing the building industry toward sustainability: a goal of lowering the emission levels emitted by the industry, and new norms and regulations on a zero-energy building. The zero-energy building concept is primarily based on the principle that the amount of renewable energy created on the site will be equal to the total amount of energy used by the building during its operational phase throughout its entire lifetime. As a result, the photovoltaic technology was introduced to the building sector, and from there started a rapid research and development of a merged field, building-integrated photovoltaics (BIPV). The market of BIPV is still young and is hence constantly changing. A few BIPV product manufacturers are steadily represented on the market, while new products and manufacturers are emerging and others disappearing now and then. A critical review presented herein provides technical information on existing BIPV products and systems, considering their multi-functionality as a climate screen, energy generator and aesthetic component. Therefore, this paper aims to help to understand BIPV products and systems as well as possibilities and challenges associated with their integration into the built environment of today, thus also giving guidelines for the development and design of BIPV components for the future.
Shifting from a Risk Mitigation Project to an Adaptation Project: The case of Curitiba’s Lagoon Parks
Authors: Perez-Lancellotti Gino , Ziede Marcela
Published: December 2020

Drawing upon the sustainability transitions theory, the paper aims to explore how the risk mitigation project of Curitiba’s lagoon parks shifted to adaptation urban projects in the context of tackling climate change. “Urban acupuncture” was the pioneering strategy adopted by Curitiba’s Municipality through the introduction, more than 40 years ago, of a limited number of low cost projects in some natural lagoons as innovative experiments that operate as a niche in a multi-level perspective. The projects acted as a way of resisting the pressure of urban intervention trends focused on transforming natural landscapes into new built-up urban areas, or intervention in natural ecosystems with water drainage and engineering solutions. These experiments and their synergy now constitute urban parks with a leverage impact on the capacity the city has to adapt to climate change, creating tension on the institutionalized regime. Through this case study, we examine the importance of governance, leadership and urban networks professionals in addition to technical features of the projects. The findings suggest that a top-down strategy, long time frame, and the exclusion of community participation have a limited likelihood of replicability and are discouraged nowadays in public urban policies. The paper contributes to highlighting the link between experimental urban acupuncture and sustainability transitions through incremental projects in natural areas for climate change adaptation. It contributes to the understanding of transitions in the southern hemisphere where institutions struggle with tight budgets, incremental interventions and specific nondemocratic contexts, and raises concerns about the critical role of governance.
Modelling the Tensile Softening Behaviour of Concrete in LS-Dyna Software
Authors: Král Petr , Hradil Petr , Kala Jiří
Published: December 2020

The problematic of the paper focuses on the numerical modelling of tensile softening behaviour of concrete. For this purpose, the explicit finite element software LS-Dyna contains several nonlinear material models. The tensile softening behaviour of a total of four selected explicit nonlinear concrete models (namely the Concrete Damage models Release 1 and Release 3, the Winfrith Concrete model and the Continuous Surface Cap model) is tested within numerical simulations of this paper. The task used within the numerical simulations is represented by so-called UUT (Unconfined Uniaxial Tension) test. For this test, specific concrete specimens are used. The numerical simulations are performed with using explicit finite elements. Results of numerical simulations are shown by l-d (load-displacement) diagrams of the UUT test for individual nonlinear concrete models. These results are compared with results obtained from the laboratory measurements for the purpose of validation of the numerical models. The comparisons enable to obtain information about differences between individual nonlinear concrete material models in terms of the tensile softening behaviour. They also show the accuracy of approximations of experimental results by numerical simulations. Based on the comparisons, it can be concluded which nonlinear material models are best for the description of behaviour of concrete in uniaxial tension. Based on the obtained results, it can further be discussed the suitability of nonlinear concrete models in terms of other tests for measuring the tensile mechanical properties of concrete.
Properties of cement-based composites with carbon mineral admixture
Authors: Kovacs Pavel , Pokorný Jaroslav , Šál Jiří , Ševčík Radek
Published: December 2020

In the construction industry, aggregates, in the form of fine powder up to gravel, play a significant role as a stabilizing and filling materials for many applications. With increasing demands on quarrying of this valuable commodity, its natural resources have become to be depleted. This work outlines the potential application of waste carbon-based mineral admixture as a partial replacement of natural silica aggregate in the production of cement-based composites. In addition, the influence of used waste material on hydration products formation in cement pastes was investigated. On hardened concretes stored 28 days under water, material properties were characterized by measuring flexural and compressive strengths. Cement pastes were subjected to X-ray diffraction analysis and scanning electron microscopy observations. Obtained results revealed specific behaviour of an incorporated material allowing its addition in a limited amount. Increased content of ettringite was detected in composites with the highest amount of added carbon-based mineral.
VOCs Emission Simulation of Common Flooring Materials
Authors: Kraus Michal , Senitkova Ingrid Juhasova
Published: December 2020

The objective of the paper is to investigate the environmental and health impacts of the common flooring materials. The paper presents a numerical simulation of volatile organic compounds (VOCs) emissions from flooring surface covering. VOCs emissions are mostly dangerous pollutants with a negative health impact on the human body and carcinogenic risk. The comparative simulation of emission for single flooring materials under standard test conditions was performed. The significant VOCs emissions from nylon carpet, linoleum, vinyl, laminate and hardwood flooring are compared. The results of a chemical analysis simulation confirmed that commonly used flooring surfaces fall into the category of polluting materials.
Digitalisation in Construction as an Educational Challenge for Universities
Authors: Lojda Jan , Němec Otakar , Nývlt Vladimír , Ližbetinová Lenka
Published: December 2020

Digitization in the construction industry has become a reality, and universities have incorporated it into their curricula. There is currently a high percentage of workers in the construction sector who are not familiar with the digital processing of documentation. The Institute of Technology and Business in České Budějovice responded to this demand with a research project of intergenerational education, which is being tested in a large construction company. Research results so far show that construction companies can be helped to educate their workers by guiding the sharing of skills and competences. The paper deals with testing the intergenerational sharing of IT competences in construction production. Testing the managed transfer of IT competences brings a new dimension to the education process that will enable accelerated adaptation of staff to the new conditions. It will help companies to reduce their training costs and enable targeted training for a specific worker. The role of the university is in the professional guarantee of the transferred competences and the management of their transfer process. The article brings experience with this new educational methodology.
Modelling Effectiveness of Environmental Greenery Systems as a Tool to Partially Eliminate Urban Overheating
Authors: Žák Jaroslav
Published: December 2020

The paper describes the first results of modelling the effectiveness of environmental greenery systems as a tool for partial elimination of urban overheating. Environmental greenery contributes to the effective management of rainwater flowing from the paved surfaces of the cities. Technical measures will reduce temperature fluctuations, noise pollution and dust concentration. The new rainwater management will contribute to reducing the temperature fluctuations, especially in summer. The evaporation of vertical environmental greenery will at least partially reduce the negative impact of the climate change. Urban greenery is one of the effective measures for urban heat island mitigation and climatic change. The numerical model gives a first idea of how large areas of environmental greenery need to be installed in order to benefit the above-mentioned benefits.
Change to bedrock modifications as a result of additional geological survey results related to the renovation of sports premises
Authors: Smugala Stanislav , Kubečková Darja , Indra František
Published: December 2020

When foundations are uncovered during a construction project, the foundation load capacity is often found not to correspond with the prescribed limit values in the project’s documentation after being compared with a given deformation module. This is often the result of a corresponding geological survey not having been conducted satisfactorily according to the given construction project’s surface area. The most common method of stabilizing bedrock, i.e. increasing the deformation module value, is lime stabilization. This method represents a suitable technical solution for modifying foundation layers, especially from an economic perspective. However, this modification method may not necessarily represent a suitable technical solution because of either the heterogeneity of underlying layers or the existence of fluctuating groundwater levels at the construction site, which can, when the final work is used, affect the mechanical and physical characteristics of the already stabilized bedrock layer.
Research on the Application of Space Information Technology in Geoheritages for Land-use Planning Purposes
Authors: He Ping , Cheng Xianfeng , Liu Yong
Published: December 2020

The application status of space information technology in geoheritage resources survey and evaluation, digital construction and environmental monitoring in China is reviewed. For improvement of the Land-use planning purposes will be used selected information. The application of spatial information technology in the acquisition of spatial and temporal data, dynamic management, image data processing, analysis and simulation prediction, and visualization of various kinds of information of geoheritage resources is increasing. With the development, planning and protection of geoheritage resources, this technological advantage will become more prominent.
Qualitative Assessment for Walkability: Duhok University Campus as a Case Study
Authors: Raswol Layla M.
Published: December 2020

The University Campus as a learning environment needs to be a safe comfortable and accessible place, where students enjoy walking and social interaction. This study evaluates the quality of walking environment by analyzing both physical features of streets sidewalks and individual perceptions of pedestrians. The research approaches to answer the question: to what extent is the University Campus safe and attractive for the students to walk? The research used mix methods and case study approach to achieve study objectives. The mix methods include onsite observation, visual survey and questionnaire with students using walkability checklist to determine the walking quality on streets sidewalks. In this regard four variables are considered based on previous literature review as; safety and pedestrians’ facilities, comfortable walking environment, walking connectivity and lastly walking attractiveness. The result shows that the lack of safety and pedestrian facilities, poor designed sidewalks and connectivity leads to low level of walkability and increase car dependency in the study area. The findings provide guidelines for increasing the efficiency of walking, in order to encourage students to choose walking over car driving.
Severity of Damage Due to 2017 Kurdistan Region of Iraq-Iran border Earthquake (Halabja Earthquake)
Authors: Abdullah Wrya , Rafiq Serwan Khorsheed , Alshkane Younis M.
Published: December 2020

On 12th of November 2017, a major earthquake of a magnitude of M 7.3 hit Halabja and caused severe structural damage and collapse in Iran, however, only a few areas of Iraq were mildly affected by it. It was considered the deadliest earthquake of the year as its casualties surpassed 400 people most of which were in Iran. Halabja, was only 32 km away from the epicenter, yet the quake caused no noticeable structural damage to the buildings and no casualties or serious injuries were reported from there. This paper presents the possible engineering reasons behind the gigantic gap of severity of the damage between Kurdistan region of Iraq and Iran. The analysis is done after a series of site visit to Darbandikhan and Halabja and taking more than 300 photographs of the damaged and collapsed buildings. Several crucial factors are discussed in detail, the major of which is directionality effects of the quake as its epicenter was in Iran and the quake caused a meter of slip towards south and half a meter of displacement towards west of the epicenter. Due to the directionality effect, the damage was more in the south and the west of the epicenter knowing that most parts of Kurdistan region of Iraq were located at the north of the epicenter. It is also found that the geological location of the buildings was insignificant in increasing the damage level of the buildings.
The Hydraulic Jump Formed Downstream a Stepped Gabion Weir: An Experimental Study
Authors: Al-Fawzy Ali Mekki , Naief Al-Taee Kadhim , Al-Mohammed Fadhil Mohammed , Hommadi Ali Hassan
Published: December 2020

The current study focus on the effect of using stepped gabion weir in a laboratory channel on the hydraulic jump distance which form at its toe. A series of 175 operation tests and 25 laboratory experiments were conducted by using a laboratory flume 10 m long, 0.3 m wide, and 0.5 m deep. The tested gabions had different five lengths 0.72 m, 0.84 m, 0.96 m, 1.08 m, and 1.20 m respectively, and the material used to fill the gabions was natural quarry mono graded gravel in five different sample sizes of diameters ranged between (09.5-14.0) mm, (14.0-19.0) mm, (19.0-25.0) mm, (25.0-37.5) mm, and (37.5-50.0) mm. The operation flow rate values ranged between 2.33*10-3to 50.00*10-3m3/s/m. Dimensional analysis was used to generate dimensionless parameters, and correlated them using the Buckingham Pi-Theorem. The results of this study showed that the hydraulic jump distance increases by increasing the flow rate value, but increasing the values of both of the gravel sample used and the total length of the weir have an undular effect on the hydraulic jump distance.
Mechanical Properties of Lightweight Concrete Made with Shredded Waste Polypropylene Yogurt Containers
Authors: Hashim Ahmed Mudhafar , Mahmood Aseel , Al-Baaji Abdullah Amar , Jamal Abdulkader Niveen
Published: December 2020

The partial replacement of natural coarse (gravel) aggregate by waste plastic aggregate to produce lightweight concrete has become one of the major challenges in recent years and stresses on the need for a constant and authoritative development for the betterment of the environment. This work was carried out to investigation the possibilities of using waste polypropylene yogurt containers as polymer aggregate in concrete application. The concrete samples with 0%, 5%, 10%, 15%, 20% and 25% recycled waste plastic aggregate as partial replacement by mass of natural coarse aggregate are prepared after a curing period of 28 days. The effect of recycled plastic aggregate on compressive strength, density and water absorption of natural concrete are studied and compared with the results of specimen without plastic aggregate. Both compressive strength and density decreased with increasing the amount of plastic aggregate. The highest reduction in compressive strength and density were 50% and 19% respectively of concrete cubes containing 25% wt polypropylene waste aggregate in comparison of traditional concrete. It was found that water absorption increased as the plastic aggregate content increased up to 15% wt and then decreased when replaced coarse aggregate by 20% wt and 25% wt by recycled polypropylene aggregate. This study is recommended to use recycled polypropylene yogurt containers as a partial substance of traditional coarse (gravel) concrete mix up to 15% wt for applications include those where low compressive strengths and low cost production are desirable.
Automated Approach for Extraction of Retinal Blood Vessels
Authors: Abdulsahib Dheyaa M. , Jaafar Hussain F.
Published: December 2020

In the field of ophthalmology, retinal image analysis is crucial to extract many details that help doctors identifying retinal diseases at early stages, such details are the blood vessels, optic disk, and fovea. The exponential increase in number of diabetic retinopathy patients necessitates the use of computers to help doctors to diagnose and treat retinal diseases of the human eyes. Computer vision effectively helps doctors by analyzing and treating human retinas. In the field of ophthalmology, a color image (RGB image) of the eye fundus is captured by ophthalmoscopy. In this work, an automatic technique for extraction of human retinal blood vessels is proposed. The proposed method is based on three main stages, namely image pre-processing, initial segmentation of blood vessels and image post-processing. In the first stage, the contrast-limited adaptive histogram equalization is applied to the green component image to improve its contrast, and then it is remerged again with the red and blue components. In the second stage, the blood vessels are extracted using mean-C thresholding. Finally, in the third stage, many morphological operations are used to refine the segmented blood vessels image. The proposed method is validated using the expert ground truths with the DRIVE dataset in terms of pixels, and experimental results show sensitivity, specificity, accuracy and positive predictive value of 0.770816, 0.977575, 0.959993 and 0.7611835, respectively. The performance measures are compared with many recent related works and found to outperform most of them. The superior performance of this method proves that it is promising for mass screening of human fundus images.
Characterization of temperature-dependent superlattice in Cu:KTN crystal
Authors: Zhang Fei , Liu Bing , Yang Cheng-Kai , Hu Yan-Yan , Zhang Hua-Di , Li Qing-Gang , Wang Xu-Ping , Zhang Yuan-Yuan , Yang Yu-Guo , Wei Lei
Published: December 2020

In this study, we grew CuO doped potassium tantalum niobate (Cu:KTN) crystals with a uniform superlattice structure by the off-center top-seeded solution growth (TSSG) method. The process of crystal superlattice structure formation was observed under a polarizing microscope at variable temperatures. It was found that the formation of the superlattice structure in the crystal was closely related to the formation process of the domain structure in the crystal. The 90° domain structure in the crystal promoted the formation of the superlattice structure in the crystal. The purpose of the formation of the superlattice structure is to enable the crystal to reach a more stable state. The clear diffraction effect of the crystal superlattice structure is similar to the x-ray diffraction phenomenon of low-temperature crystals, and it exists in the crystal in a three-dimensional structure.
A simple proof of curvature estimate for convex solution of 𝑘-Hessian equation
Authors: Chu Jianchun
Published: December 2020

Guan-Ren-Wang [Comm. Pure Appl. Math. 68 (2015), pp. 1287–1325] established the curvature estimate of convex hypersurface satisfying the Weingarten curvature equation

σ

k

(
κ
(
X
)
)
=
f
(
X
,
ν
(
X
)
)

\sigma _{k}(\kappa (X)) = f(X,\nu (X))

. In this note, we give a simple proof of this result.
Nonexistence of variational minimizers related to a quasilinear singular problem in metric measure spaces
Authors: Garain Prashanta , Kinnunen Juha
Published: December 2020

In this article we consider a variational problem related to a quasilinear singular problem and obtain a nonexistence result in a metric measure space with a doubling measure and a Poincaré inequality. Our method is purely variational and to the best of our knowledge, this is the first work concerning singular problems in a general metric setting.
New results on the prefix membership problem for one-relator groups
Authors: Dolinka Igor , Gray Robert
Published: December 2020

In this paper we prove several results regarding decidability of the membership problem for certain submonoids in amalgamated free products and HNN extensions of groups. These general results are then applied to solve the prefix membership problem for a number of classes of one-relator groups which are low in the Magnus–Moldavanskiĭ hierarchy. Since the prefix membership problem for one-relator groups is intimately related to the word problem for one-relator special inverse monoids in theEE-unitary case (as discovered in 2001 by Ivanov, Margolis and Meakin), these results yield solutions of the word problem for several new classes of one-relator special inverse monoids. In establishing these results, we introduce a new theory of conservative factorisations of words which provides a link between the prefix membership problem of a one-relator group and the group of units of the corresponding one-relator special inverse monoid. Finally, we exhibit the first example of a one-relator group, defined by a reduced relator word, that has an undecidable prefix membership problem.
Pollination by Non-ApisBees and Potential Benefits in Self-Pollinating Crops
Authors: Esquivel Isaac L , Parys Katherine A , Brewer Michael J
Published: December 2020

The diversity and abundance of native bees (Hymenoptera: Anthophila) are important in providing pollination services to a diverse array of crops. An extensive literature base is available on the contributions of bees as crop pollinators. The focus of the majority of these studies are on honey bees (Apis spp.) pollinating crops that depend on cross-pollination to produce a yield. Self-pollinating crop species, including cotton, soybeans, coffee, and canola, can self-pollinate but there is increasing evidence that they can also benefit from cross-pollination by insects. These crops can see a considerable benefit when visited by bees in general, but contradictory evidence is not fully understood in some systems. For example, recent studies have shown that bee visitation to cotton blooms can increase yield up to 15%. Including nesting habitat for non-Apis bees within soybean dominated landscapes increases in-field yields. However, in these same systems, some studies show none or minimal yield increases. Additional literature (both recent and historical) of non-Apis bees in mass-flowering self-pollinating crops and their potential benefits to the crops also exists but is previously unsynthesized in cotton and soybeans in particular. In our review of literature on these select self-pollinating crops, there appears to be apparent gaps in the literature base on these and other understudied cropping systems. With the exception of graminaceous and cereal crops, all the crops discussed herein seem to have all have benefited from visitation by both Apis and non-Apis bees. Some provide known resource benefits to native bee pollinators like canola, but others like cotton and soybean are not well understood. Further, with an apparent yet small literature base in cotton and soybean there are many facets between the native bee pollinators and crop such as nutritional benefits of nectar and pollen to the bees themselves that still need to be addressed. To examine these underlying mechanisms, additional studies into the basic biology and natural history, including nesting habitats and preferences along with foraging preferences of abundant bee species will help understand how these bees seem to persist and possibly thrive in intensified agricultural systems.