bluuebunny/crossref_metadata_2025 huggingface dataset:
Photovoltaic and impedance spectroscopy characterization of single-junction a-Si:H p–i–n solar cells deposited by simple shadow masking techniques using PECVD
Authors: Belrhiti Alaoui Kawtar , Laalioui Saida , Naimi Zakaria , Ikken Badr , Outzourhit Abdelkader
Published: September 2020

Hydrogenated amorphous silicon p–i–n solar cells with a 1 × 1 cm2 active surface area were fabricated using shadow masks on the 20 × 20 cm2 glass substrate coated with a fluorine-doped tin oxide film. The intrinsic, n-type hydrogenated amorphous silicon (a-Si:H), and p-type a-SiC:H thin films were deposited using plasma-enhanced chemical vapor deposition at 13.56 MHz plasma excitation frequency and on 20 × 20 cm2 and SnO2:F covered glass substrates. Low rf-power densities (less than 0.1 W/cm2) and substrate temperatures (less than 190 °C) were used for this purpose. Raman spectra of the films are dominated by a broad peak around 480 cm−1 that is the characteristic of the amorphous silicon network for all the three types of films. Scanning electron microscopy measurements revealed that the surface of the a-Si:H films deposited on SnO2:F-coated glass substrates (Asahi-VU) replicates the texture of the SnO2:F film. Spectroscopic ellipsometry spectra were analyzed with the Tauc–Lorentz dispersion model, and the results revealed that the optical gap of the intrinsic a-Si:H films is on the order of 1.7 eV, while that of the a-SiC:H is on the order of 1.8 eV. These results were further confirmed by optical transmission measurements. The highest efficiency obtained for solar cells prepared with shadow masking under our condition is on the order of 8.83% with a Voc of 0.856 V, a short circuit current density of 15.6 mA/cm2, and a fill factor of 66.07%. The obtained efficiency is slightly lower than the record efficiency obtained in this family of cells (10.3%) prepared by laser scribing because the low short-circuit current slightly lowers the fill factor. Impedance spectroscopy measurements were performed on the cells in the dark in the frequency range of 1 kHz–100 kHz. The analysis of impedance either in the Nyquist diagram or in the Bode diagram suggests a lumped circuit consisting of resistance Rs in series with a parallel combination of resistance Rp and capacitance Cp that account for the p–i–n structure. The value of Rp changed with the applied DC bias. The value of the series resistance agrees with the value obtained from the current–voltage characteristics of the cell.
Shock wave in one-dimensional dusty plasma crystal with charge gradient
Authors: Niu Q. L. , Tian M. , Chen H.
Published: September 2020

In this paper, the effect of charge gradient in a one-dimensional dusty plasma crystal is considered to investigate shock structure. Under the continuum limit, the nonlinear Korteweg–de Vries (KdV)–Burgers equation with a charge gradient effect is derived using the reductive perturbation method. Then, the shock solution based on the KdV–Burgers equation is obtained. The influence of the parameter ε, which measures the effect of charge gradient on the dynamic of the shock wave, is discussed in detail. It is found that the shock amplitude and strength increase with the increase in the parameter ε. Furthermore, it is also found that charge gradient effect makes oscillatory shock more easily converted to monotonic shock.
Composition-aware spectroscopic tomography
Authors: Pfister Luke , Bhargava Rohit , Bresler Yoram , Carney P Scott
Published: September 2020

Chemical imaging provides information about the distribution of chemicals within a target. When combined with structural information about the target, in situ chemical imaging opens the door to applications ranging from tissue classification to industrial process monitoring. The combination of infrared spectroscopy and optical microscopy is a powerful tool for chemical imaging of thin targets. Unfortunately, extending this technique to targets with appreciable depth is prohibitively slow. We combine confocal microscopy and infrared spectroscopy to provide chemical imaging in three spatial dimensions. Interferometric measurements are acquired at a small number of focal depths, and images are formed by solving a regularized inverse scattering problem. A low-dimensional signal model is key to this approach: we assume the target comprises a finite number of distinct chemical species. We establish conditions on the constituent spectra and the number of measurements needed for unique recovery of the target. Simulations illustrate imaging of cellular phantoms and sub-wavelength targets from noisy measurements.
Anti-frosting and defrosting performance of chemically modified super-nonwettable carbon soot coatings
Authors: Esmeryan Karekin D , Gyoshev Stanislav D , Castano Carlos E , Mohammadi Reza
Published: September 2020

The inherent hydrophilicity of a variety of heat exchanging industrial appliances, including air-conditioners, refrigerators or heat pumps, is a highly-beneficial platform for the accumulation of frost at negative surface temperatures, dramatically aggravating the efficient device operation in terms of heat transfer and energy consumption. Here, we introduce experimental data from pioneering research on the frosting/defrosting behavior of chemically modified super-nonwettable soot—one of the very few materials providing scalability, satisfactory mechanical durability, icephobic and anti-bioadhesion properties simultaneously. The analysis of the anti-frosting/defrosting performance of three groups of soot coatings, obtained by treating the pristine samples with alcohol, fluorocarbon or silver hydrogen fluoride, reveals that the frost incipiency on the soot can be efficiently controlled by tailoring its chemistry and porosity. In turn, the super-nonwettable material is capable of delaying the onset of vapor condensation and frosting to supercooling degrees of 8.4 °C and 15.8 °C, accordingly, and maintaining relatively large frost-free halos up to −20 °C. Moreover, the onset of soot defrosting is accelerated by a factor of 35 compared to a bare Cu substrate, demonstrating extremely low ice adhesion forces and strong potential of the soot coatings for passive icing protection of many cryogenic facilities.
Discharge characteristics of two-stage micro-cathode arc MPD thrusters with a permanent magnet and a pulsed magnetic field
Authors: Zolotukhin D , Daniels K , Keidar M
Published: September 2020

Small, lightweight low-power micro-cathode arc thrusters (µCATs) with micronewton thrust are well suited to the altitude control of small satellites like CubeSats. For some applications (orbit raising, maneuvering) their thrust level needs to be improved. A possible approach for this could be the two-staged thruster—a micro-cathode thruster with a magnetoplasmadynamic (MPD) stage and an external magnetic field. In this article, we discuss some discharge features that such a two-stage µCAT-MPD experiences in each configuration of the magnetic field—formed with either a permanent magnet, or a pulsed magnetic coil. We found that in both configurations of the magnetic field, the thrust can be enhanced significantly (up to factor of 10) after some threshold voltage is applied to the second stage. The pulsed magnetic coil ensures better controllability of the magnetic field; however, it causes an undesirable time delay between the plasma generation moments in both stages, which consequently results in a moderate thrust increase. The permanent magnet provides a stable thrust increase; however, it cannot be switched off, which seems to be impractical for its use in micro-satellites. In both magnetic field configurations, the emissive electromagnetic noise level was found to be low-frequency (within tens of kHz) and quite moderate in amplitude, and mechanical noise was found to be two orders of magnitude lower than the thrust generated in the normal working regime.
Many-body interference in bosonic dynamics
Authors: Dufour Gabriel , Brünner Tobias , Rodríguez Alberto , Buchleitner Andreas
Published: September 2020

We develop a framework to systematically investigate the influence of many-particle interference on the dynamics of generic—possibly interacting—bosonic systems. We consider mixtures of bosons which belong to several distinguishable species, allowing us to tune the level of many-particle interference, and identify the corresponding signatures in the time-dependent expectation values of observables. Interference contributions to these expectation values can be classified based on the number of interfering particles. Interactions are shown to generate a series of additional, higher-order interference contributions. Finally, based on a decomposition of the Hilbert space of partially distinguishable bosons into irreducible representations of the unitary group, we determine some spectral characteristics of (in)distinguishability.
Nonlinear radiative bioconvection flow of Maxwell nanofluid configured by bidirectional oscillatory moving surface with heat generation phenomenon
Authors: Chu Yu-Ming , Aziz Samaira , Khan M Ijaz , Khan Sami Ullah , Nazeer Mubbashar , Ahmad Iftikhar , Tlili Iskander
Published: September 2020

The current communication explore the nonlinear thermal radiation and heat absorption/generation aspects in rate type nanofluid containing gyrotactic microorganism. The bidirectional periodically moving surface induced the flow. The nonlinear radiation features are elaborated in the heat equation. With applications of apposite primarily quantities, the governed equations are transmuted into non-dimensional form. The homotopic procedure is followed to result the simulation analysis. A comprehensive physical analysis is performed for velocity, nanofluid temperature, concentration distribution and motile microorganism profile. The numerical evaluation for change in heat, mass and motile microorganisms is carefully examined with appliance of various graphs and tables. The observations yield out from current contribution reveal that relaxation parameter and Hartmann number declined the both velocity components. The mixed convection constant sufficiently improves the velocity in contrast to buoyancy ratio forces. The surface heating parameter, Brownian constant and bouncy ratio constant improves the nanofluid temperature. An opposing trend in motile microorganism is noted with Peclet constant and bioconvected Lewis number.
Engineering the photoelectrochemical behaviors of ZnO for efficient solar water splitting
Authors: Ma Mengmeng , Huang Yanbin , Liu Jun , Liu Kong , Wang Zhijie , Zhao Chao , Qu Shengchun , Wang Zhanguo
Published: September 2020

Solar water splitting is a promising strategy for the sustainable production of renewable hydrogen and solving the world’s crisis of energy and environment. The third-generation direct bandgap semiconductor of zinc oxide (ZnO) with properties of environmental friendliness and high efficiency for various photocatalytic reactions, is a suitable material for photoanodes because of its appropriate band structure, fine surface structure, and high electron mobility. However, practical applications of ZnO are usually limited by its high recombination rate of photogenerated electron–hole pairs, lack of surface reaction force, inadequate visible light response, and intrinsic photocorrosion. Given the lack of review on ZnO’s application in photoelectrochemical (PEC) water splitting, this paper reviews ZnO’s research progress in PEC water splitting. It commences with the basic principle of PEC water splitting and the structure and properties of ZnO. Then, we explicitly describe the related strategies to solve the above problems of ZnO as a photoanode, including morphology control, doping modification, construction of heterostructure, and the piezo-photoelectric enhancement of ZnO. This review aims to comprehensively describe recent findings and developments of ZnO in PEC water splitting and to provide a useful reference for the further application and development of ZnO nanomaterials in highly efficient PEC water splitting.
Regulation of surface properties of photocatalysis material TiO2 by strain engineering
Authors: Zheng Jian , Shu Dajun
Published: September 2020

As a promising photocatalysis material, TiO2 has long been studied by experimental and theoretical methods. The external strain could affect the catalytic reactivity of TiO2 significantly due to the difference in surface elastic properties of different surface structures with different surface adsorption or defects. This article reviews our recent work by using density function theory calculations on the effect of strain on the TiO2 surface properties, including surface relative stability, surface defects, surface adsorption and dissociation.
Recent progress in organic electrodes for zinc-ion batteries
Authors: Xu Shuaifei , Sun Mingxuan , Wang Qian , Wang Chengliang
Published: September 2020

Organic zinc-ion batteries (OZIBs) are emerging rechargeable energy storage devices and have attracted increasing attention as one of the promising alternatives of lithium-ion batteries, benefiting from the Zn metal (low cost, safety and small ionic size) and organic electrodes (flexibility, green and designable molecular structure). Organic electrodes have exhibited fine electrochemical performance in ZIBs, but the research is still in infancy and hampered by some issues. Hence, to provide insight into OZIBs, this review summarizes the progress of organic cathode materials for ZIBs and points out the existing challenges and then addresses potential solutions. It is hoped that this review can stimulate the researchers to further develop high-performance OZIBs.
Rational design of multinary copper chalcogenide nanocrystals for photocatalytic hydrogen evolution
Authors: Fu Hao , Tang Aiwei
Published: September 2020

Photocatalytic hydrogen evolution is one of the most promising ways to solve environmental problems and produce a sustainable energy source. To date, different types of photocatalysts have been developed and widely used in photocatalytic hydrogen evolution. Recently, multinary copper chalcogenides have attracted much attention and exhibited potential applications in photocatalytic hydrogen evolution due to their composition-tunable band gaps, diverse structures and environmental-benign characteristics. In this review, some progress on the synthesis and photocatalytic hydrogen evolution of multinary copper chalcogenide nanocrystals (NCs) was summarized. In particular, considerable attention was paid to the rational design and dimensional or structural regulation of multinary copper chalcogenide NCs. Importantly, the photocatalytic hydrogen evolution of multinary copper chalcogenide NCs were reviewed from the aspects of energy level structures, crystal facets, morphology as well as composition. Finally, the current challenges and future perspectives of copper chalcogenide were proposed.
Pedestal structure, stability and scalings in JET-ILW: the EUROfusion JET-ILW pedestal database
Authors: Frassinetti L. , Saarelma S. , Verdoolaege G. , Groth M. , Hillesheim J.C. , Bilkova P. , Bohm P. , Dunne M. , Fridström R. , Giovannozzi E. , Imbeaux F. , Labit B. , de la Luna E. , Maggi C. , Owsiak M. , Scannell R. ,   JET contributors
Published: September 2020

The EUROfusion JET-ILW pedestal database is described, with emphasis on three main issues. First, the technical aspects are introduced, including a description of the data selection, the datasets, the diagnostics used, the experimental and theoretical methods implemented and the main definitions. Second, the JET-ILW pedestal structure and stability are described. In particular, the work describes the links between the engineering parameters (power, gas and divertor configuration) and the disagreement with the peeling-ballooning (PB) model implemented with ideal magnetohydrodynamics equations. Specifically, the work clarifies why the JET-ILW pedestal tends to be far from the PB boundary at high gas and high power, showing that a universal threshold in power and gas cannot be found but that the relative shift (the distance between the position of the pedestal density and of the pedestal temperature) plays a key role. These links are then used to achieve an empirical explanation of the behavior of the JET-ILW pedestal pressure with gas, power and divertor configuration. Third, the pedestal database is used to revise the scaling law of the pedestal stored energy. The work shows a reasonable agreement with the earlier Cordey scaling in terms of plasma current and triangularity dependence, but highlights some differences in terms of power and isotope mass dependence.
High frequency Alfvén eigenmodes detected with ion-cyclotron-emission diagnostics during NBI and ICRF heated plasmas on the ASDEX Upgrade tokamak
Authors: Ochoukov R. , Bilato R. , Bobkov V. , Chapman S.C. , Dendy R. , Dreval M. , Faugel H. , Kappatou A. , Kazakov Ye.O. , Mantsinen M. , McClements K.G. , Moseev D. , Nielsen S.K. , Noterdaeme J.M. , Salewski M. , Schneider P. , Weiland M.
Published: September 2020

The paper presents the first reported observation of high frequency Alfvén eigenmode excitation on the ASDEX Upgrade tokamak. The mode is driven in a novel way using radio frequency (RF) wave acceleration of either beam-injected deuterium ions or thermal He-3 minority ions in a three-ion heating scenario. In the case of beam ion acceleration, the instability only appears during deuteron acceleration at the third beam ion cyclotron harmonic (wave frequency ω = 3ΩD where ΩD is the deuterium cyclotron frequency), as the mode is not detected during the more commonly used second harmonic/minority heating scenario or in the absence of beam-injected ions. The mode frequency is around 0.6–0.7ΩD, where ΩD is evaluated in the low-field side plasma edge, and tracks the magnetic field B and the edge plasma electron density ne via the Alfvénic relation ω ∼ B ne
−1/2. The mode does not appear as a single frequency wave but as a bundle of closely spaced (in frequency) sub-modes. When the parallel beam ion velocity component is increased, the sub-mode frequency spacing is observed to decrease, possibly due to a change in the eigenmode structure. Under certain conditions, typically in discharges with a relatively low plasma current, IP
< 0.7 MA, the mode appears to be driven directly by sub-Alfvénic deuterium beam ions. Absolute measurements of the mode amplitude show that at least 1% of the beam-injected power is transferred non-collisionally to the instability. While this is too low for practical alpha-channeling applications, discharges are planned with the aim of increasing the level of power transferred non-collisionally between fast ions and the instability.
Numerical Analysis of Geogrid and Deep Mixing Column Supported Embankment
Authors: Albusoda Bushra S. , Hussein Samir H. , Al-Hamdani Dhurgham A.
Published: September 2020

Embankment is an essential component of civil engineering constructions. It is required for the implementation of many projects such as roads, railways, and dams. However, large deformations and lateral movements may occur due to the poor mechanical properties of the weak soils. To avoid that, the subgrade must be improved. One of the efficient and economic techniques that solve these problems is the column-supported embankment system. In this paper, a numerical model of the embankment was established using (ABAQUS) software program. Three different modes were studied to explain the behavior of these embankments. A parametric study was conducted to examine the various influencing factors, such as elastic modulus of columns, the effect of the geogrid layer on the performance of embankment, the settlements, the lateral movement, the shear strength of the soil, the stress concentration ratio, the soil arching ratio, and the tension force in geogrid layer were determined and analyzed for various embankment modes. The results show that the effect of the elastic modulus of columns plays a vital role in the performance of the embankment. Similarly, the geogrid layer also has significant effects on the lateral displacement, and the shear strength of the embankment. In general, for all modes, the decrease in the elastic modulus of the columns leads to an increase in the embankment loads that carried out by the soil between the columns. While, the absence of the geogrid layer leads to an increase in the embankment loads carried by columns.
Effects of Sandy Soil-structure Interaction on the Natural Period of RC Building Frames
Authors: Fadhil Aqeel T. , Al-Zaidee Salah R. , Jasim Mustafa M.
Published: September 2020

Building natural period, T, is a key character in building response for wind and seismic induced forces. In design practice, the period, T, is either estimated from empirical relations proposed by the design codes or determined from analytical or numerical models. The effect of the soil-structure interaction is usually neglected in the design practice and analysis models. This paper uses a sophisticated finite element simulation to investigate the effect of soil-structure modeling on the fundamental period of RC buildings subjected to wind and seismic induced forces. A typical interior building frame has been imitated using the frame element for beams and columns with constrains to model the almost-rigid diaphragm nature for floors and roof while a three-dimensional element has been adopted for the raft foundation and the soil mass. Different sandy soils have been considered. Standard Penetration Test, SPT value, has been taken as an identification index for soil nature. All other soil properties have been estimated based on well-accepted correlations. After applying the gravity dead and live loads, and eigenanalysis has been achieved to show how soil flexibility affects the effective stiffness of the structure and the corresponding natural period. Finally, the results are used to introduce a correction factor to modify the natural period estimated from a linear analysis with ideal supports to reflect the aforementioned effects.
Erosion, Sediments Transport and Riverbank Stability: A Review
Authors: Aldefae Asad H. , Al-Khafaji Rusul A. , Shamkhi Mohammed S. , Kumar Haider Q.
Published: September 2020

This paper is a review of the basic theoretical information needed to understand the riverbank stability, failure mechanism, and its causes. The first part describes the basic principles of river systems involving river hydraulics, sediment load, and channel morphology. This is pursued by a brief discussion concerning riverbank erosion that involves theoretical equations and numerical methods to quantify erosion. Finally, an in-depth discussion concerning riverbank stability that involves the types of failure mechanism, tension cracks, and riverbank settlement is conducted. Also, the paper reviews some previous studies on riverbank stability.
Assessment of the Three-Dimensional Model Produced by Photogrammetric and Geodetic Surveying Techniques
Authors: Khalaf Yousif Hussein , Abdulateef Nagham Amer
Published: September 2020

A combination of close-range photogrammetry techniques and geodetic surveying techniques are used to produce the three-dimensional model, which is one of the major tasks in the field of surveying at present because it is used in many engineering applications, industrial, medical and in cultural heritage objects which requires regular monitoring because of the high accuracy and reliability needed to conduct the measurements. The study area was in the university of Baghdad, specifically for the building of the university tower this research has been produced the three dimensional model of the tower depending on the overlapping ground images captured by a digital camera and the total station instrument used to measure the coordinates of ground points distributed on the university of Baghdad tower. The mathematical model used in this study is the direct linear transformation method to intensify ground points which are used to produce the three-dimensional model of the university tower. Also, a photogrammetric program is used to compute the object space coordinates from the point cloud three-dimensional modeling.
Modeling of Estimate at Completion in Earned Value
Authors: Baqer Sabreen Mortadha , Rezouki Sedqi Esmaeel
Published: September 2020

This paper will explain the concept of Earned value management and definition of the influenced factor, earned worth management (EVM) is an associate trade commonplace for observance the performance of in progress comes. The performance baseline is about up within the designing section to live any time and price deviations throughout project execution. supported this progress, associate estimate at completion (EAC) is forecasted, investigate a wide range of factors impact on earned value in different countries, especially in Iraq and the region to reduce cost project in estimate to complete and estimate at complete, which helps decision-makers to make the right decision to reduce costs, achieve planned duration and taking into account other aspects.
Using BIM for Optimizing the Upgrading Cost to Convert the Traditional Buildings to Sustainable Buildings in Iraq
Authors: Abdulrasool Sarah Ahmed , Raoof Mahjoob Ahmed Mohammed
Published: September 2020

A high percentage of existing buildings in Iraq are traditional buildings, yet there is approximately no such green building in Baghdad or other governorates. Most of these buildings require urgent upgrading to increase their performance (operationally, economically, and environmentally), also the building owners looking for identifying and implementing many of the green building measures to reduce the operational and maintenance costs of their buildings. The decision-makers need to support the possibility of achieving sustainable measures of existing building rating systems such as LEED or BREEAM, and that would require an optimization model. The goal of this study is to maximize the building’s operational efficiency, health, and comfort of the building to its occupants through minimizing upgrading cost and reducing the environmental impacts of the building. An existing building will be used as a case study to illustrate the optimization process and demonstrate the plans and processes required to achieve the green building measures, the capability of reducing the required upgrade costs. For this type of problem, the building drawings are represented Using Building information modeling (BIM) (Revit program), and the life cycle costing and environmental impact can be found using analytical tools (ONE CLICK LCA STUDENT VERSION online software). The results show that up to (15.4 and 23.2) % reduction in discounted and nominal costs respectively could be achieved, the CO2 emissions also had decreased from 34233 Ton to 19299 Ton.
Developing Systems Engineering for Sustainable Infrastructure Projects
Authors: Obead Khamael R. , Wali Meervat R.
Published: September 2020

Globally, Sustainability is very quickly becoming a fundamental requirement of the construction industry as it delivers its projects; whether buildings or infrastructures. Throughout more than two decades, many modeling schemes, evaluation tools, and rating systems have been introduced en route to realizing sustainable construction. Many of these, however, lack consensus on evaluation criteria, a robust scientific model that captures the logic behind their sustainability performance evaluation, and therefore experience discrepancies between rated results and actual performance. Moreover, very few of the evaluation tools available satisfactorily address infrastructure projects. The research introduces a system engineering model that abstracts the environment, the construction product, and its production system as three interacting systems that exchange materials, energy, and information. The model utilizes this setup to capture and quantify essential flows exchanged between such three systems, to evaluate sustainability. The research walks through the development of a generic case of the model, and then demonstrates its utility in evaluating the sustainability performance of civil infrastructure projects. The developed model will address an identified gap within the current body of knowledge by considering infrastructure projects. Through the ability to simulate different scenarios, the model will enable identifying which activities, products, and processes impact the environment more, and hence potential areas for optimization and improvement.
The Law of Decentralization and Its Impact on Construction Projects
Authors: Abed Emad Essa , Mohammed Sawsan Rasheed
Published: September 2020

Decentralization is a democratic practice in which the Government allows ministries, governorates and districts to delegate their powers within the law. This is done in two parts: the first is the decentralization of the operational budget and the second the decentralization of the investment budget. This study aims to draw up a strategy and plan for decentralization in the governorates after the transfer of powers from the ministries. The researcher seeks to discover the success or failure of applying this idea and the importance of modern construction projects in the study of decentralization in these ministries in selected governorates. Transfer of powers This research is very important through the selection and timing, and is important in that this study is the first to target the impact of decentralization on the performance of construction projects. Despite the existence of previous studies and research on administrative decentralization, it did not address the impact of decentralization and its role in the process of implementation and completion of projects. The research methodology was divided into two parts, theoretical work and fieldwork. The researcher concluded that there is a need for decentralization in particularly in the governorates far from the central government. However, these conditions are subject to limitations and restrictions. They can only be applied after studying the presence of human cadres and providing expertise that deals with post-transfer jobs. The absence of Iraqi government legislation in this area and even if we assume there are laws, they have not been applied so far about the system of decentralization in Iraq in its entirety.
Developing a Computer Program to Solve the Implementation Problems of Public Investment Projects in Iraq
Authors: Almissary Sanaa M. , Burhan Abbas M.
Published: September 2020

The implementation of public investment projects in Iraq in terms of cost and time specified within the general investment budget and in terms of quality; requires analysis the obstacles facing the implementation of these projects and propose appropriate solutions to them through developing a proposed program to analyze and address the problems through project phases. The aim of research for developing a computer program comprises the identified problems as input to the program and the proposed treatments as output for it; to facilitate the work of the departments involved in projects in making decisions and to avoid repeat the previous mistakes. The researcher conducted personal interviews to identify (55) problems facing the public investment projects in Iraq grouped in (5) groups; legal and administrative, financial, technical, problems with documentary credits and other problems, conducting questionnaire survey to clarify the impact of these problems on the implementation process, using a statistical program (SPSS) to compute relative important index (RII) for them to identify the group that most impact on the implementation of public investment projects. A visual basic program with database (SQL) was utilized to analyze and treat the problems related to the subject of research. This program is equipped with the ability to withdraw reports on projects as (word, pdf, or excel). The results from research showed that there is (absences coordination between different service departments, delays in land acquisition procedures for projects, weakness of the possibility of most consultancy offices designed for projects, weakness of personals specialized in the preparation of technical and economic feasibility studies and inaccuracy of signed contracts with contractors… etc.).
Quantifying and Modeling the Cumulative Impact of Changes Order for the Projects in Iraq
Authors: Hassan Soadad M. R. , Rezouki Sedqi Esmaeel
Published: September 2020

This research investigates the change orders projects of hospital construction in Iraq, for several reasons. Because these types of projects have a relatively long duration, which leads to a change in some requirements or the emergence of new developments with the owner or gets a new technical development in this field, also these projects contain a large number of documents, specifications, plans, bill of quantities, and a large number of engineers with various specializations participate in preparing them, which makes the probability of change possible due to the large work and poor coordination between those specializations or the development of new government regulations. This current research is based on a database of eleven projects for hospitals. The researcher used combined methodology: the qualitative method represented by interviews of many construction professionals, and the quantitative method represented by questionnaire surveys and gathering data through a survey the documents of change orders for the projects. In this study, we adopted the analytical statistical approach by used F-tests and then used a one - way ANOVA analysis. The researcher managed to reach mathematical models that can predict the added cost of change requests that occur through the planning or implementation phase for the project, to avoid or minimize project changes. A series of statistical model selection criteria were applied to carefully identify the best models, for ease of use of search results and to obtain a tool that can be used by the parties to the project.
Isolation and Identification of Local Bactria Produced from Soil-Borne Urease
Authors: Ali N. A. , Karkush M. O. , Al Haideri H. H.
Published: September 2020

The hydrolysis of urea by the enzyme urease is significant for increasing the irroles in human pathogenicity, biocementation, soil fertilizer, and subsequently in soil improvement. This study devoted to the isolation of urease from urea-rich soil samples collected from seven different locations. Isolation of the various bacterial species was conducted using nutrient agar. The identity of isolated urease was based on morphological characteristics and standard microbiological and biochemical procedures. The urease producing strains of bacteria were obtained using the urease hydrolysis test. The bacterial isolates produced from soil samples collected from different environments and treated by different morphological processes helped in precipitation of large calcium carbonate (CaCO3) crystal aggregates precipitated within bacterial colonies grown on agar. The different microbial species and functional attributes produced striking differences in the morphology of precipitated crystals. The phylogenetic sequencing of 16S ribosomal RNA genes produced several isolates that are mostly related to the Bacillus group. One strain of promising results was selected and the environmental and nutritional conditions were characterized. The growth curve of the selected strain with an optimized condition was investigated.
Sustainability Assessment System for Highrise Buildings in Iraq
Authors: Habib Hussain M. , Erzaij Kadhim R.
Published: September 2020

This study aims to preparation a standards code for sustainability requirements to contribute in a better understanding to the concept of sustainability assessment systems in the dimensions of Iraqi projects in general and in the high-rise building. Iraq is one of the developing countries that faced significant challenges in sustainability aspects environmental, economic and social, it became necessary to develop an effective sustainability building assessment system in respect of the local context in Iraq. This study presented a proposal for a system of assessing the sustainability requirements of Iraqi high rise buildings (ISHTAR), which has been developed through several integrated steps, begin with investigates the well-known sustainability systems, experts consensus based on the Delphi technique involving 32 experts consider as sustainability world leading and local highly-informed to identify applicable assessment categories and factors for the Iraqi context and its weighting system, then analyze the results using the pairwise comparison and Analytic Hierarchy Process (AHP) technique.
Ergonomics elements and their influence in the garment industry
Authors: Barbu I , Fogorasi M S , Bucevschi A , Nicolaescu C
Published: September 2020

Apart from the strict elements related to the organization of the work place of the equipment and operated machines, the productivity of an operator or factory is addiction on other elements of ergonomics such as: temperature and relative humidity of the air, speed of air currents, noise level, level vibrations and their directions, CO2 level, brightness, radiation level, chromatic from the production hall, ambient music and its volume. In this paper we analyzed the influence of light intensity and ambient music on productivity in a clothing section in which 70-80 workers manufacture sports equipment in which dark colours predominate, for children, women and men. Some levels of light intensity were chosen, different from those provided in standards (400 lx for light colours and 700 lx for dark colours), and for ambient music we chose as a volume level, with 5-10 dB above the average noise level in the production hall. We mention that in this section is not used ambient music currently. We mention that all the laboratory equipment used are in the SIProM laboratory, (study, hygiene and labor protection ), within the Faculty of Engineering, and the collective of this study was an interdisciplinary one formed by researchers from the Textile Industry field and a researcher from the Accounting field. Initially, timings were made to determine the execution times for certain technological phases, namely: the overlock machine, the elastic applicator machine and the simple machine, for zipper application. These measurements were made under the usual working conditions in this hall production, for lighting levels of 550-750 lx and without ambient music. At the end of the study, data on labour efficiency were processed and calculations were made regarding labour costs for workers who served the three types of machines. For a complete image of the activity of the entire section, production department, the information was processed for the entire section, both in terms of productivity per worker, for each machine, and the costs for manpower were calculated for the nine weeks of the our study. For a more complete information of the activity of the whole section, the results were extended for the whole section, both in terms of efficiency per worker, for each machine and the costs for the work of the entire group of workers were calculated.
The mechanism’s study of fixing a container on a freight wagon type Rgs
Authors: Berescu C , Fratila C , Axinte T , Diaconu M , Cojocaru R
Published: September 2020

In freight transport is constantly evolving in the world. An important role in development of freight transport is the increasing usually a speed to 180 km/h of freight trains. In multimodal transport, all the goods are transported in containers. Therefore, the freight is mostly containerized. Several containers in freight trains are transported on Rgs freight wagons. On Rgs platforms of freight wagons are bolts of which the containers are fixed. The role of these bolts is very important because when the train takes the curve or brakes ward, containers could leave the wagon’s platform. In this paper, we represented a Rgs Wagon loaded with two containers. We have to mention that the dimensions of wagon and containers have been made using original projects. Furthermore, we are approached the theoretical aspects referring to the clamping system. We set out to accomplish a through search of both the used bolt to Rgs wagons and new model of bolt. This research was caried out with the help of finite elements method. The design part and the study with finite elements were made in NX 12 software from Siemens. Because of these bolts types they following stress: normal, shear and von Mises. As a consequence, we deduced that the second bolt type is more reliable.
Mechanical characterization of additive manufactured samples from biodegradable materials
Authors: Carausu C , Mazurchevici S-N , Mazurchevici A-D , Andrusca L , Comaneci R , Popa R-I , Nedelcu D
Published: September 2020

One of the biggest challenges facing engineers and designers in the field of additive manufacturing is to constantly develop and promote new products to meet the increasingly varied and demanding needs of customers. They must also “navigate” through a wide variety of technologies and materials available in order to determine the most appropriate solution for their application. The best and easiest way to determine if a particular technology or material is right for an application is to study and understand its behavior. This paper aims to mechanical characterize 3D printed samples from biodegradable materials through tensile, bending, and impact tests but also by determining the mechanical behavior in the dynamic regime and the tribological behavior (friction coefficient and wear). For the obtained results during the tensile test were performed a statistical analysis of the technological parameters’ influence on the output parameters (tensile strength, strain, and modulus of elasticity) and it has been developed and the optimization of these ones. The studied biodegradable thermoplastics were bioFila Linen, bioFila Silk and Fiber Wood which according to the highlighted results can be used in various fields of activity and can easily replacing polymers from fossil resources such as flexible filaments, high impact polystyrene, polypropylene, polypropylene reinforced with short glass fibers, polymers reinforced with metal or wood powder.
The optimization of container transport on a ship type PSV
Authors: Cojocaru R , Axinte T , Fratila C , Diaconu M , Berescu C
Published: September 2020

In this paper, we studied how containers need to be transported on a PSV ship. The deterioration of the containers during the transport can get a result in the destruction on the goods. All the drawings were made by us in the NX 12 software from Siemens. Furthermore, the analysis of the container clamping system was performed by the finite element method using the NX 12 Siemens software. Structural dimensions following an original project, were used to the achievement of a PSV (Platform Supply Vessel) ship in design. Although, PSV ships are relatively small, they have a complex design. The purpose of these ships types is to transport freight and weights bigger and bigger. This is the reason why we close to present in this work only the optimization of containers on PSV ships.
An accurate and fast iterative scheme for estimating the ship rolling and capsizing in regular waves
Authors: Deleanu D , Panaitescu M , Panaitescu F V
Published: September 2020

A short number of steep breaking waves hitting a ship from the side may affect its dynamic behaviour and to determine extreme roll angles and, eventually, capsizing. This last phenomenon is a challenging task for naval engineers because it is responsible not only for a lot of material damages, but also for human lives. It is therefore not surprising that there have been published many relevant theoretical and experimental studies on heavy rolling and capsizing but the problem is not yet fully resolved. Generally, the ship rolling in beam regular seas could be described by a second-order non-linear differential equation with the roll angle as dependent variable. Non-linearity comes from the restoring and damping moments, which are usually represented by (odd) polynomials of roll angle or of its time derivative. Numerical integrators incorporated in modern software packages (e.g. ode45 in Matlab) encounter efficiency problems for the unbounded solutions associated with capsizing, the running time being extremely high. The alternative is to write a computer software, appropriate to the topic to be solved. In the paper, the roll equation was solved using a simple, fast and accurate iterative scheme based on Taylor expansion. Compared with Runge-Kutta 4th order numerical technique, the used scheme demonstrated not only an excellent agreement of the results, but also a significant reduction of the CPU time. The rapidity of the scheme allowed us to conduct a comprehensive investigation on fractal erosion of safe basins and to represent the normalized integrity curves and the amplitude-frequency response curves for different combinations of wave parameters. The restoring and damping coefficients corresponded to a vehicle ferry model, considered to be either intact or damaged, on the one hand, and with or without bilge keels, on the other.
Materials used in a naval collision calculation with finite element software
Authors: Dumitrache C L , Faitar C , Buzbuchi N , Dumitrache R
Published: September 2020

Collisions and groundings have a significant contribution to structural damages occurring to ships. For collision calculation are used non-linear relations between strains and deformations, considering a significant difference between the initial shape and final deformed shape of the structure, and the mechanical equilibrium equations are written on the deformed shape of the structure. Using a mechanical test to a material sample will result the connection between the engineering strain and engineering deformation. During numerical simulation, we are using the real mechanical characteristic curve, which represents the reliance between real strains and real deformations, those being calculated from the distorted material sample. For calculation, we are using Johnson – Cook plasticity model, frequently used by other authors as well during collision calculation. There is included new information, also tabular calculations using specific formulas, resulted during carried out studies, to establish the model parameters considering the measured data or using information from another material model (exponential law). Considering the materials used within ANSYS software and calculus processor LS-DYNA, are presented types of materials useful for collision calculation, describing the elasticity, plasticity and yielding. Following, it is used a procedure for dynamic explicit calculus because it is suitable for solving of nonlinear systems. During simulation with finite element of the collision, there are no strains and deformations concentrations and it is necessary to generate an artificial curve, which leads to same results, as in reality and as well finite element analysis.