bluuebunny/crossref_metadata_2025 huggingface dataset:
MEASUREMENT OF MICROCHANNELS PRODUCED IN AA6351/RUTILE COMPOSITE BY WIRE-EDM
Authors: SREERAJ P. , THIRUMALAI KUMARAN S. , SURESH KUMAR S. , UTHAYAKUMAR M. , PETHURAJ M.
Published: August 2020

The fabrication of microchannels, in order to dissipate the heat flux generated in the complex parts of an electronic industry, requires considerable attention since it is a complex process. Some advanced machining process like wire electrical discharge machining (WEDM) has been employed carefully for forming channels in material. However, the surfaces of these microchannels play an important role in dissipating heat energy. The present study focusses on the fabrication of AA6351/10[Formula: see text]wt.% Rutile MK grade mineral through powder metallurgy route, and their properties are evaluated. In addition, the forming of microchannels on the fabricated composite has also been done through WEDM process under varying machining conditions. WEDM process conditions considered are current, voltage and wire speed, and the response characteristics are kerf width, surface roughness and kerf depth. The hybrid approach of gray-based Taguchi coupled with PCA has been considered for optimizing the process parameters so as to get near net shape channels. The determined hardness of the composite is 64.5[Formula: see text]HB and the compressive strength is 220[Formula: see text]MPa. The optimized conditions are predicted and the regression model has been developed.
EFFECT OF FRICTION STIR PROCESSING (FSP) ON THE WEAR BEHAVIOR OF CAST AS21A MAGNESIUM ALLOY
Authors: JOSHI SUMIT , SINGH RAMESH CHANDRA , CHAUDHARY RAJIV
Published: August 2020

The contemporary trend of cost-saving is the primary motive while studying the relative motion between the material surfaces. Therefore, exceptional surface characteristics are the most desirable features for any material. The rapid emerging surface modification phenomena like Friction Stir Processing (FSP) have proved its potential in the surface engineering applications. In this study, Magnesium–Aluminum–Silicon (Mg–Al–Si)-based AS21A magnesium alloy was examined for the wear characterization in respect with the cast and Friction Stir Processed (FSPed) conditions. FSP, performed at an optimized set of parameters, was utilized to attain the surface modification in the investigated material. In the wear study, cast and FSPed conditions of AS21A specimens were examined on Pin-on-disc apparatus with typical load values ranging from 10–40[Formula: see text]N. The subsequent investigation involves characterization of worn surfaces through Scanning Electron Microscope (SEM) micrographs, and Energy Dispersive X-Ray Spectrometer (EDS) to understand the accountable wear mechanism. It was found that the FSPed AS21A samples exhibited noteworthy improvement in the wear characteristics at all assessment conditions. FSPed sample showed overall 17% enhancement in the specific wear rate. Also, with an increase in normal load, around 53–55% reduction was observed in the Coefficient of Friction (COF) value. It was established that the morphology of Mg2Si precipitates had an active contribution in the wear behavior of cast and FSPed AS21A samples. The notable mechanisms found responsible for the wear of samples were adhesion, abrasion, oxidation, delamination and plastic deformation.
PREVALENCE OF MUSCULOSKELETAL INJURIES IN PARTICIPANTS ENROLLED IN ZUMBA-BASED TRAINING
Authors: Sawant Swara , Kolke Sona
Published: August 2020

Purpose: Our study aimed to find the location and pattern of musculoskeletal injuries in participants enrolled in Zumba-based training and to analyze the contributing risk factors for injuries through a self-administered questionnaire. Methods: A total of 50 participants were recruited in an offline and online-based study using a self-administered questionnaire based on seven demographic-based questions, eight injury-related questions and five questions based on the risk factors related to Zumba-based training. Binomial logistic regression analysis was used to predict the odds-ratio and factors contributing to the risk of injuries. Results: Twenty-nine out of 50 participants (58%) had single or multiple musculoskeletal injuries with the most common sites of injury being in the order of: leg (23%), knee (18%) and ankle, foot and the lower back (15%). Amongst the injured subjects, 10 (34.4%) had sought medical help and 11 (37.9%) had resorted to self-management. The binomial regression analysis showed the presence of recurrent injuries and the flooring of the class to be significantly associated with the risk of injuries. Conclusion: There was a 58% prevalence of musculoskeletal injuries in the subjects enrolled in Zumba-based training. The factors which are found to be an increased risk for musculoskeletal injuries were recurrent injuries and flooring of the class.
Electric Field Effects on Buckling Analysis of Boron–Nitride Nanotubes Using Surface Elasticity Theory
Authors: Zeighampour Hamid , Tadi Beni Yaghoub , Kiani Yaser
Published: August 2020

In this paper, the axial buckling of boron nitride nanotubes (BNNTs) is investigated by considering the effects of surface and electric field. To achieve this purpose, the surface elasticity theory is exploited and the results are compared with the molecular dynamic simulation in order to validate the accuracy of the applied theory. In the molecular dynamics simulation, the potential between boron and nitride atoms is considered as Tersoff type. The Timoshenko beam theory is adopted to model BNNT. Moreover, two types of zigzag and armchair BNNTs are considered. In this study, the effects of surface, electric field, length, and thickness of BNNT on the critical buckling load are investigated. According to the results, the critical load of zigzag BNNT depends on the electric field. However, the electric field would not affect the critical load of the armchair BNNT. It should be noted that the surface residual tension and surface Lamé’s constants of BNNT have considerable impact on the critical load of BNNT. For lower values of electric field and smaller dimensions of BNNT, the critical load would be more dependent on the surface effect regarding the results. Furthermore, as an efficient non-classical continuum mechanic approach, the surface elasticity theory can fill the potential gap between the classical continuum mechanic and molecular dynamics simulation.
Structural Health Monitoring Using Synchrosqueezed Wavelet Transform on IASC-ASCE Benchmark Phase I
Authors: Sanchez Wilson D. , de Brito Jose V. , Avila Suzana M.
Published: August 2020

Civil structures suffer deterioration either for years of service, deficiency due to environmental factors or damages caused by factors such as earthquakes, winds, impact loads, and cyclical loads. When a structure ages, it is necessary to know its state of health and make a decision of maintenance or replacement. When a structure such as a bridge or building is subjected to destructive environmental forces, determining its state of health becomes a priority since its recovery is urgently required to function normally. Structural Health Monitoring (SHM) is a technology that aims to prevent the collapse of structures and loss of human life through early diagnosis of the health status of a structure. There are a large number of damage detection methods that can be classified into (1) non-destructive testing methods, (2) dynamic characteristics-based damage detection methods, (3) dynamic response-based, (4) multi-scale damage detection method and (5) damage detection methods with consideration of uncertainties. In this work, it is implemented synchrosqueezed wavelet transform (SWT), which can be classified as a methods based on the dynamic response. To validate the robustness of the method it is identified first, the natural frequencies of the Benchmark Phase I without damage, which consists of a steel structure of 4-story [Formula: see text] bay 3D steel frame structure subjected to ambient vibrations. Subsequently, some damage patterns are validated according to IASC-ASCE SHM Task Group. The results obtained in the identification of natural frequencies are compared with those reported in literature. SWT was efficient, presenting a minimum error of 0.12[Formula: see text] and a maximum of 3.06[Formula: see text] in the identification of natural frequencies about the AISCE-ASCE group model. SWT overcomes some other damage detection methods, which are deficient in the identification of closely spaced frequencies, commonly present in many civil structures due to symmetric geometry or similar physical properties in different directions.
Quantum B-algebras with involutions
Authors: Ciungu Lavinia Corina
Published: August 2020

The aim of this paper is to define and study the involutive and weakly involutive quantum B-algebras. We prove that any weakly involutive quantum B-algebra is a residuated poset. As an application, we introduce and investigate the notions of existential and universal quantifiers on involutive quantum B-algebras. It is proved that there is a one-to-one correspondence between the quantifiers on weakly involutive quantum B-algebras. One of the main results consists of proving that any pair of quantifiers is a monadic operator on weakly involutive quantum B-algebras. We investigate the relationship between quantifiers on bounded sup-commutative pseudo BCK-algebras and quantifiers on other related algebraic structures, such as pseudo MV-algebras and bounded Wajsberg hoops.
Characteristics of Earthquake Input Energy of a Subway Station Structure Based on Probability Density Evolution Method
Authors: Liu Z. Q. , Chen Z. Y. , Zhao H.
Published: August 2020

Understanding seismic energy input and dissipation mechanism is necessary for energy-based seismic design of complex underground structures. Due to the intrinsic uncertainty of ground motion, stochastic methods are usually needed. In this paper, we study the seismic energy input and dissipation mechanism in an underground structure using the probability density evolution method (PDEM). It is found that the cumulative hysteretic energy dissipation ([Formula: see text] of the underground structure is reduced by 55% compared with the above-ground structure due to soil constraint. The columns, walls and slabs at the bottom of the underground structure have a high demand for [Formula: see text], which are vulnerable spots of the structure.
Numerical Simulation of Viscous Flows Around a Surface Combatant Model at Different Drift Angles Using Overset Grids
Authors: Wang Jianhua , Liu Zhenghao , Wan Decheng
Published: August 2020

Viscous flows around ship hull is of great complexity, and when the ship is advancing with drift angles, the flow field can be more complicated. In this paper, the viscous flow field around an obliquely towed surface combatant DTMB 5512 is computed using the unsteady Reynolds-averaged Navier–Stokes (URANS) method. The numerical simulations are carried out by the in-house CFD solver naoe-FOAM-SJTU, which is developed on the open source platform OpenFOAM. To refine local grids and simulate dynamic ship motions, the overset grid approach is applied. Grid convergence study is first performed at straight-ahead towed condition with three sets of grid number and the results show monotonically convergence. Six different drift angles for the DTMB 5512 model at Froude number of 0.28 are simulated and the predicted hydrodynamic forces and flow field are presented. During the simulation, the ship hull is free to trim and sinkage at a free surface environment. As for straight-ahead towed condition, the total resistance coefficient and flow field, i.e., wave pattern and wake region, between this work and the experiment are compared. Both force coefficients and flow field show good agreement with the available experimental data. For oblique towed conditions, the lateral force, yaw moment and the derived hydrodynamic derivatives are also presented and compared with the experimental results. The variation of wave pattern and wake region at different drift angles are presented and analyzed. The results show that the current approach can be an effective tool to predict the viscous flows and hydrodynamic loads for oblique towed ships.
Calculation of Stress/Displacement Field of Mechanical Joint Structure Based on Layered Elastic Theory
Authors: Yang Yang , Sun Qingchao , Fan Zhihao , Zhang Xianlian , Wang Lintao
Published: August 2020

Various types of machinery are not a continuous whole, but are assembled from various parts according to specific requirements. The surfaces that contact each other between different parts are often called mechanical joints. The stress/displacement field of the mechanical joint structure is the basis for predicting the mechanical properties of the assembly, optimizing the structure and the assembly process, and the existence of the mechanical joint surface destroys the continuity of the whole structure, which challenges the traditional calculation based on elastic mechanics. In view of the discontinuity of mechanical joints and the material difference of the parts matched with each other, this paper based on the layered elastic theory (LET), the discontinuity of the mechanical joint surface and the difference of the materials of the joint parts are analyzed. The mechanical joints are described by layers on the basis of the analysis of the discontinuity of typical mechanical joints. The stress and displacement equations are established by combining the surface characteristic parameters, and the established equations are solved by setting the boundary conditions. The calculation model of the stress/displacement field of the joint surface under the normal load is obtained. Finally, the model is used to calculate the experimental setting joint surface’s pressure distribution. In this paper, pressure distribution tests and finite element simulation are carried out on the joints with the same parameters. The results show that the model can accurately obtain the stress/displacement distribution law of the joints. The model can be directly used to calculate the pressure and displacement of the joint and the internal component. This model provides an effective method to analyze the stress and deformation of discontinuous structures, the distribution of pressure interface and the slip of interface. It can be directly used to calculate the joint position and the internal pressure and displacement of components, and the calculation efficiency is high.
Root lattices in number fields
Authors: Popov Vladimir L. , Zarhin Yuri G.
Published: August 2020

We explore whether a root lattice may be similar to the lattice [Formula: see text] of integers of a number field [Formula: see text] endowed with the inner product [Formula: see text], where [Formula: see text] is an involution of [Formula: see text]. We classify all pairs [Formula: see text], [Formula: see text] such that [Formula: see text] is similar to either an even root lattice or the root lattice [Formula: see text]. We also classify all pairs [Formula: see text], [Formula: see text] such that [Formula: see text] is a root lattice. In addition to this, we show that [Formula: see text] is never similar to a positive-definite even unimodular lattice of rank [Formula: see text], in particular, [Formula: see text] is not similar to the Leech lattice. In Appendix B, we give a general cyclicity criterion for the primary components of the discriminant group of [Formula: see text].
Relative hyperbolicity for automorphisms of free products and free groups
Authors: Dahmani François , Li Ruoyu
Published: August 2020

We prove that for a free product G with free factor system [Formula: see text], any automorphism [Formula: see text] preserving [Formula: see text], atoroidal (in a sense relative to [Formula: see text]) and none of whose power send two different conjugates of subgroups in [Formula: see text] on conjugates of themselves by the same element, gives rise to a semidirect product [Formula: see text] that is relatively hyperbolic with respect to suspensions of groups in [Formula: see text]. We recover a theorem of Gautero–Lustig and Ghosh that, if G is a free group, [Formula: see text] an automorphism of G, and [Formula: see text] is its family of polynomially growing subgroups, then the semidirect product by [Formula: see text] is relatively hyperbolic with respect to the suspensions of these subgroups. We apply the first result to the conjugacy problem for certain automorphisms (atoroidal and toral) of free products of abelian groups.
Primal-dual based distributed approximation algorithm for Prize-collecting Steiner tree
Authors: Saikia Parikshit , Karmakar Sushanta , Pagourtzis Aris
Published: August 2020

The Prize-collecting Steiner tree (PCST) problem is a generalization of the Steiner tree problem that finds applications in network design, content distribution networks, and many more. There are a few centralized approximation algorithms [D. Bienstock, M. X. Goemans, D. Simchi-Levi and D. Williamson, A note on the prize collecting traveling salesman problem. Math. Program. 59 (1993) 413–420; M. X. Goemans and D. E. Williamson, A general approximation technique for constrained forest problems, SIAM J. Appl. Math. 24(2) (1995) 296–317; D. S. Johnson, M. Minkoff and S. Phillips, The prize collecting Steiner tree problem: Theory and practice, in Proc. Eleventh Annual ACM-SIAM Symp. Discrete Algorithms, SODA ’00 (2000), pp. 760–769; A. Archer, M. Hossein Bateni and M. Taghi Hajiaghayi, Improved approximation algorithms for prize-collecting Steiner tree and TSP, SIAM J. Comput. 40(2) (2011) 309–332] for solving the PCST problem. However, the problem has seen very little progress in the distributed setting; to the best of our knowledge, the only distributed algorithms proposed so far are due to Rossetti [N. G. Rossetti, A first attempt on the distributed prize-collecting Steiner tree problem, M.Sc. thesis, University of Iceland, Reykjavik (2015)]: one of them fails to guarantee a constant approximation factor while the other one is essentially centralized. In this work, first, we present a deterministic [Formula: see text] factor distributed approximation algorithm (D-PCST algorithm) that constructs a PCST for a given connected undirected graph of [Formula: see text] nodes with non-negative edge weights and non-negative prize value for each node. The D-PCST algorithm is based on the primal-dual method and uses a technique of preserving dual constraints in a distributed manner, without relying on knowledge of the global structure of the network. For an input graph [Formula: see text], the round and message complexities of the D-PCST algorithm in the CONGEST model are [Formula: see text] and [Formula: see text] respectively, where [Formula: see text] and [Formula: see text]. Furthermore, we modify the D-PCST algorithm and show that a [Formula: see text]-approximate PCST can be deterministically computed using [Formula: see text] rounds and [Formula: see text] messages in the CONGEST model, where [Formula: see text] is the unweighted diameter of [Formula: see text]. For networks with [Formula: see text], the modified D-PCST algorithm performs better than the original one in terms of the round complexity. Both the algorithms require [Formula: see text] bits of memory in each node, where [Formula: see text] is the maximum degree of a node in the graph.
Doubly connected bi-domination in graphs
Authors: Abdlhusein Mohammed A.
Published: August 2020

Let [Formula: see text] be a finite graph, simple, undirected and has no isolated vertex. A dominating subset [Formula: see text] of [Formula: see text] is said a bi-dominating set, if every vertex of it dominates two vertices of [Formula: see text]. The bi-domination number of [Formula: see text], denoted by [Formula: see text] is the minimum cardinality over all bi-dominating sets in [Formula: see text]. In this paper, a certain modified bi-domination parameter called doubly connected bi-domination and its inverse are introduced. Several bounds and properties are studied here. These modified dominations are applied and evaluated for several well-known graphs and complement graphs.
A supportive electrostatic model of the COVID-19 airborne transmission
Authors: Lattarulo Francesco
Published: August 2020

A mechanism-oriented model is proposed here as a speculative but robust attempt to understand whether there might be any increased risk of electrostatically induced contamination, with relevant consequences from the epidemiological viewpoint. This could also be the case for the COVID-19 spreading because an amount of micro-sized droplet nuclei, often carrying net electric charge, are expected to be electro-dynamically involved in a physical process originated by the natural and unperceivable static electrification of human beings. The effects of the triboelectric charging have long been successfully tested because the phenomenon under examination is also implied in the genesis of the electrostatic discharge (ESD), a demanding key objective in the special context of electromagnetic compatibility (EMC). Therefore, the ultimate purpose of this technical paper is to provide valuable insights into infection control, building on what is already being done for maintaining static-safe environments. The stature of the applied model can be further appreciated because some currently observed climate-dependent and sex-linked different vulnerabilities to COVID-19 are critically examined by unique sound arguments. These ultimately focus attention on ambient relative humidity and worn shoes, the latter differing for typology, size and material, for their integrated control of the inadvertent human aptitude to buildup tribocharges. These would appear as a dreadful prerequisite for charge bearing droplets in the airborne state to be efficiently attracted/repelled according to the described electrostatic mechanism.
WHAT THE FUTURE MIGHT HOLD: DISTRIBUTIONS OF REGIONAL SECTORAL DAMAGES FOR THE UNITED STATES — ESTIMATES AND MAPS IN AN EXHIBITION
Authors: YOHE GARY , WILLWERTH JACQUELINE , NEUMANN JAMES E. , KERRICH ZOE
Published: August 2020

The text and associated Supplemental Materials contribute internally consistent and therefore entirely comparable regional, temporal, and sectoral risk profiles to a growing literature on regional economic vulnerability to climate change. A large collection of maps populated with graphs of Monte-Carlo simulation results support a communication device in this regard — a convenient visual that we hope will make comparative results tractable and credible and resource allocation decisions more transparent. Since responding to climate change is a risk-management problem, it is important to note that these results address both sides of the risk calculation. They characterize likelihood distributions along four alternative emissions futures (thereby reflecting the mitigation side context); and they characterize consequences along these transient trajectories (which can thereby inform planning for the iterative adaptation side). Looking across the abundance of sectors that are potentially vulnerable to some of the manifestations of climate change, the maps therefore hold the potential of providing comparative information about the magnitude, timing, and regional location of relative risks. This is exactly the information that planners who work to protect property and public welfare by allocating scarce resources across competing venues need to have at their disposal — information about relative vulnerabilities across time and space and contingent on future emissions and future mitigation. It is also the type of information that integrated assessment researchers need to calibrate and update their modeling efforts — scholars who are exemplified by Professor Nordhaus who created and exercised the Dynamic Integrated Climate-Economy and Regional Integrated Climate-Economy models.
Design and Fabrication of a Dual Rotor-Embedded Wing Vertical Take-Off and Landing Unmanned Aerial Vehicle
Authors: Wong Seng Man , Ho Hann Woei , Abdullah Mohd Zulkifly
Published: August 2020

The interest in building hybrid Unmanned Aerial Vehicles (UAVs) is increasing intensively due to its capability to perform Vertical Take-Off and Landing (VTOL), in addition to forward flight. With this capability, the hybrid UAVs are highly on demand in various industries. In this paper, a fixed-wing VTOL UAV with a novel configuration of a dual rotor-embedded wing was designed and developed. The methodology used in the design process adopted the traditional sizing and aerodynamic estimation method with advanced computational simulations and estimation approaches. The design was determined based on a thorough analysis of weight contribution, aerodynamics, propulsion, and stability and control. The results show that the UAV’s preliminary design has successfully reached a total weight of 1.318 kg, achieved a high lift-to-drag ratio of approximately 4, and ensured stable flights with Level 1 flying qualities. A fixed-wing VTOL prototype was developed and fabricated based on the final design parameters using a low-cost hand lay-up process.
Buspirone decreases susceptibility to hypocapnic central sleep apnea in chronic SCI patients
Authors: Maresh Scott , Prowting Joel , Vaughan Sarah , Kruppe Elizabeth , Alsabri Bander , Yarandi Hossein , Badr M. Safwan , Sankari Abdulghani
Published: August 2020

This research study is novel as it is the first study in a humans that we are aware of that demonstrates the ability of Buspirone to increase CO2 reserve and hence decrease susceptibility to hypocapnic central apnea in patients with spinal cord injury.
Intermuscular coherence between homologous muscles during dynamic and static movement periods of bipedal squatting
Authors: Kenville Rouven , Maudrich Tom , Vidaurre Carmen , Maudrich Dennis , Villringer Arno , Ragert Patrick , Nikulin Vadim V.
Published: August 2020

It is largely unexplored how the central nervous system achieves coordination of homologous muscles of the upper and lower body within a compound whole body movement, and to what extent this neural drive is modulated between different movement periods and muscles. Using intermuscular coherence analysis, we show that homologous muscle functions are mediated through common oscillatory input that extends over alpha, beta, and gamma frequencies with different synchronization patterns at different movement periods.
Low‐Cost Solutions for Assessment of Flash Flood Impacts Using Sentinel‐1/2 Data Fusion and Hydrologic/Hydraulic Modeling: Wadi El‐Natrun Region, Egypt
Authors: Sadek Mohammed , Li Xuxiang , Mostafa Eman , Freeshah Mohamed , Kamal Ahmed , Sidi Almouctar Mohamed Adou , Zhao Fubo , Mustafa Elhadi K.
Published: August 2020

Flash floods are among the most common natural hazards in Egyptian and Arabian deserts. In this work, we utilized two Sentinel‐1 and Sentinel‐2 satellite images, before and after the flash flood, SRTM, and geolocated terrestrial photos captured by volunteers. This paper aims to three substantial objectives: (1) monitoring the flash flood impacts on Wadi El‐Natrun region based on free satellite data and mapping the destroyed vegetation cover; (2) the integration of the free remote sensing data, geolocated terrestrial photos, and GIS techniques, along with hydrologic and hydraulic modeling, to evaluate the impact of flash flood hazards on the study area; and (3) assistance of the decision‐makers in planning the required protective works to avoid the probable flooding. Two scenarios have been applied to estimate the flash flood effect. The first scenario has relied on Sentinel‐1/2 data fusion before and after the flash flood, while the second scenario has been implemented based on the integration of the Sentinel‐2 images and hydrologic and hydraulic flood modeling with the help of ArcGIS software to simulate the flash flood route. The results demonstrated that although the first scenario is an efficient solution for continuous monitoring of the change in the water bodies, it is limited in the detection of the submerged vegetation area. On the other hand, the second scenario provided the flash flood route and hydrological parameters, which determine the hazard degree of the basins, thus helping the decision‐maker to manage the flood risk. Moreover, the second scenario surpasses the first one by estimating the destroyed infrastructure. Consequently, the second scenario is appropriate to assess the flash flood impacts and mitigate its influence in the future.
Numerical Investigation of Fracture Network Formation under Multiple Wells
Authors: Men Xiaoxi , Li Jiren
Published: August 2020

A two-step fracturing method is proposed to investigate the hydraulic fracture evolution behavior and the process of complex fracture network formation under multiple wells. Simulations are conducted with Rock Failure Process Analysis code. Heterogeneity and permeability of the rocks are considered in this study. In Step 1, the influence of an asymmetric pressure gradient on the fracture evolution is simulated, and an artificial structural plane is formed. The simulation results reflect the macroscopic fracture evolution induced by mesoscopic failure; these results agree well with the characteristics of the experiments. Step 2, which is based on the first step, investigates the influence of preexisting fractures (i.e., artificial structural planes) on the subsequent fracturing behavior. The simulation results are supported by mechanics analysis. Results indicated that the fracture evolution is influenced by pressure magnitude on a local scale around the fracture tip and by the orientation and distribution of pore pressure on a global scale. The constant pressure in wellbore H2 can affect fracture propagation by changing the water flow direction, and the hydraulic fractures will propagate to the direction of higher local pore pressure. Furthermore, the artificial structural planes influence the stress distribution surrounding the wellbores and the hydraulic fracture evolution by altering the induced stresses around the preexisting fractures. Finally, fracture network is formed among the artificial structural planes and hydraulic fractures when multiple wells are fractured successively. This study provides valuable guidance to unconventional reservoir reconstruction designs.
Identification of Behavioral Features of Bridge Structure Based on Static Image Sequences
Authors: Deng Guojun , Zhou Zhixiang , Chu Xi , Shao Shuai
Published: August 2020

This paper aims to further enhance the accuracy and efficiency of large bridge structural health monitoring (SHM) through noncontact remote sensing (NRS). For these purposes, the authors put forward an intelligent NRS method that collects the holographic geometric deformation of the test bridge, using the static image sequences. Specifically, a uniaxial automatic cruise acquisition device was designed to collect the dynamic and static images on bridge facade under different damage conditions. Considering the strong spatiotemporal correlations of the sequence data, the relationships between the time history images in six fixed fields of view were identified through deep learning under spatiotemporal sequences. On this basis, the behavioral features of the bridge structure were obtained under vehicle load. Finally, the global holographic deformation of the test bridge and the envelope spectrum of the global holographic deformation were derived from the deformation data. The research results show that the output data of our NRS method were basically consistent with the finite‐element prediction (maximum error: 11.11%) and dial gauge measurement (maximum error: 12.12%); the NRS method is highly sensitive to the actual deformation of the bridge structure under different damage conditions and can capture the deformation in a continuous and accurate manner. Compared with the limited number of measuring points, holographic deformation data also shows higher sensitivity in damage identification.
Bioelectrical Impedance Analysis to Increase the Sensitivity of Screening Methods for Diagnosing Cancer Cachexia in Patients with Colorectal Cancer
Authors: Szefel J. , Kruszewski W. J. , Szajewski M. , Ciesielski M. , Danielak A.
Published: August 2020

Background. Currently used methods for detecting and monitoring cancer cachexia (CC) are not sensitive enough. In this field, there is a need to implement new instruments into clinical practice. Objective. Determining the usefulness of bioelectrical impedance analysis (BIA) for detecting and monitoring CC in patients with colorectal cancer (CRC). Methods. 158 people were invited to the study (70 from CRC and 88 controls). Their body composition was determined using BIA, and their nutritional status was determined according to NRS 2002, SGA, and BMI criteria. For statistical data analysis, Student’s t-test, Mann–Whitney U test, and AUC ROC were used. Results. Men with CRC stage I had higher values of FMI, SMMI, and ECW/TBW (p<0.05) than in stages II–IV, and women with CRC stage I had higher values of FMI, FFMI, and FM/FFM than in the group of stages II–IV (p<0.05). The ability of FFMI to detect malnutrition relative to SGA was low (sensitivity: women 40%, men 40% and specificity: women 74%, men 70%). Conclusions. SGA and NRS 2002 scales are dynamic and consider changes in nutritional status over time, while BIA is static and does not consider these changes. Therefore, BIA is not a good tool for screening nutritional status. BIA successfully identifies differences in body composition depending on cancer stage and advancement of CC. Therefore, after the diagnosis CRC, just to monitor the disease advancement and state of CC, it is worth comparing the results of periodically repeated BIA.
Multitime Resolution Hierarchical Attention-Based Recurrent Highway Networks for Taxi Demand Prediction
Authors: Chen Baiping , Li Wei
Published: August 2020

Taxi demand forecasting is an important consideration in building up smart cities. However, complex nonlinear spatiotemporal relationships in demand data make it difficult to construct an accurate prediction model. Considering that a single time resolution may not enable accurate learning of the time pattern of taxi demand, we expand the time series prediction model in our proposed multitime resolution hierarchical attention-based recurrent highway network (MTR-HRHN) model, using three time resolutions to model temporal closeness, period, and trend properties of demand data to capture a more comprehensive time pattern. We evaluate the MTR-HRHN on a taxi trip record dataset and the results show that the forecasting performance of the MTR-HRHN exceeds that of eight well-known methods in the short-term demand prediction in some high-demand regions.
Electronic, Structural, and Optical Properties of Zinc Blende and Wurtzite Cadmium Sulfide (CdS) Using Density Functional Theory
Authors: Edossa Teshome Gerbaba , Woldemariam Menberu Mengasha
Published: August 2020

Zinc blende (zb) and wurtzite (wz) structure of cadmium sulfide (CdS) are analyzed using density functional theory within local density approximation (LDA), generalized gradient approximation (GGA), Hubbard correction (GGA + U), and hybrid functional approximation (PBE0 or HSE06). To assure the accuracy of calculation, the convergence test of total energy with respect to energy cutoff and k-point sampling is performed. The relaxed atomic position for the CdS in zb and wz structure is obtained by using total energy and force minimization method following the Hellmann–Feynman approach. The structural optimization and electronic band structure properties of CdS are investigated. Analysis of the results shows that LDA and GGA underestimate the bandgap due to their poor approximation of exchange-correlation functional. However, the Hubbard correction to GGA and the hybrid functional approximation give a good bandgap value which is comparable to the experimental result. Moreover, the optical properties such as real and imaginary parts of the dielectric function, the absorption coefficient, and the energy loss function of CdS are determined.
Eye Manifestations of Shprintzen–Goldberg Craniosynostosis Syndrome: A Case Report and Systematic Review
Authors: Choi Jamie H. , Li Rachel , Gannaway Rachel , Causey Tahnee N. , Harrison Anna , Couser Natario L.
Published: August 2020

Shprintzen–Goldberg craniosynostosis syndrome (SGS) is a rare autosomal dominant condition that was first documented in literature in 1982. The disorder is caused by pathogenic variants in the proto-oncogene SKI gene, a known suppressor of TGF-β activity, located on chromosome 1p36. There is considerable phenotypic overlap with Marfan and Loeys–Dietz syndromes. Common clinical features of SGS include craniosynostosis, marfanoid habitus, hypotonia, dysmorphic facies, cardiovascular anomalies, and other skeletal and connective tissue abnormalities. Ocular manifestations may include hypertelorism, downslanting palpebral fissures, proptosis, myopia, and ectopia lentis. We describe a 25-year-old male with the syndrome. Genetic analysis revealed a novel c.350G>A (p.Arg117His) de novo variant, which was predicted to be pathogenic by the CTGT laboratory. The patient presented with dysmorphic features, marfanoid habitus, severe joint contractures, mitral valve insufficiency, aortic root dilatation, and a history of seizures. His ocular manifestations included hypertelorism, downslanting palpebral fissures, bilateral ptosis, and high myopia. Ophthalmic manifestations are an integral component of the syndrome; however, they have not been well characterized in the literature. From a systematic review of previously published cases to date, we summarize the eye and ocular adnexa manifestations reported.
Effects of Parameter Uncertainties on Interaction between Submarine Telecommunication Cables and Lateral Seabed Movements
Authors: Fu Cuiwei , Qin Xiaogang , Wang Yu
Published: August 2020

Submarine telecommunication cables are the physical backbone of the Internet. They are often buried shallowly beneath seabed and affected by seabed movements. Due to the long distance of cables and the complexity of submarine environment, interaction between cables and seabed movements inevitably involves various parameter uncertainties. However, effects of parameter uncertainties on submarine cable responses to seabed movements have not been fully investigated. This paper aims to address this problem using random finite element method (RFEM) that integrates finite element (FE) analysis with Monte Carlo simulation (MCS). First, deterministic FE analysis is performed to investigate cable responses to lateral seabed movements. Then MCS is implemented to study the effects of parameter uncertainties on cable responses. Statistical analysis of the MCS results is performed to prioritize the effects of parameter uncertainties on cable damage probability. Random field is also used to model spatial variability of soil parameters. Effect of the correlation length on cable damage probability is investigated. The results show that uncertainty of the anchored cable length La has the most significant effect on cable damage probability, while the effects of uncertainties in soil friction angle ϕ and effective unit weight γ′ are minor. Ignoring spatial variability of soil parameters may lead to significant misjudgment of cable damage risk.
Parameter Recognition of Mode-Converted Wave in Single-Source Ultrasound Using Gabor Transform for Bolt Axial Stress Evaluation
Authors: Chen Ping , He Xingliang , Song Wei
Published: August 2020

In this paper, a novel parameter recognition method of mode-converted wave in single-source ultrasound is put forward and applied to the estimation of axial stresses in bolts. To overcome the distortion and aliasing of the mode-converted wave in single-source ultrasonic signal, a time-frequency parameter recognition method based on the Gabor transform is introduced to recognize the accurate time of flight (TOF) of the mode-converted wave. Based on the mode conversion of the single-source longitudinal ultrasound, a new nonlinear evaluation model based on acoustoelastic equation is derived to determine the axial stress of bolt. The performance of the proposed method is evaluated by comparing it with the commonly used TOF ratio method of longitudinal wave and shear wave (L-S). The experiment result shows that the proposed method is more effective in detecting the connection status of bolted joints than the traditional L-S method.
The Relationship between Bus Drivers’ Improper Driving Behaviors and Abnormal Vehicle States Based on Advanced Driver Assistance Systems in Naturalistic Driving
Authors: Wang Tao , Chen Yuzhi , Yan Xingchen , Chen Jun , Li Wenyong
Published: August 2020

In order to improve the adaptation of driver to the advanced driver assistance system (ADAS) and optimize the active safety control technology of vehicle under man-computer cooperative driving, this paper investigated the correlation between driver’s improper driving behaviors and abnormal vehicle states under the ADAS. Based on the warning data collected from the driver’s assistance warning system equipped on buses, the interaction between improper behaviors, between abnormal vehicle states, and between improper behaviors and abnormal vehicle states were quantitatively analyzed through the hierarchical clustering method and improved Apriori algorithm. The results showed that eye closure and yawn were high in concurrency (probability: 0.888) and interaction (average probability: 0.946); the interaction among lane departure, rapid acceleration, and rapid deceleration are frequent (average probability: 0.7224); eye closure (average probability: 0.452) and yawn (average probability: 0.444) are likely to induce abnormal vehicle states such as rapid acceleration and rapid deceleration. Some suggestions proposed based on the results are as follows. First, it is suggested that the ADAS should combine the warning modes of eye closure and yawn; second, when the driver closes eyes or yawns, the control of the ADAS over the lateral and longitudinal performance of vehicle should be enhanced; third, the extent of control by the ADAS should be determined according to the relationship probability; finally, the lateral control over the vehicle by the ADAS should be strengthened when there is a forward collision warning.
Objetivos de Desarrollo Sostenible: ¿desafío o prioridad?
Authors: Sharoni Rosenberg
Published: August 2020

El artículo entrega una visión de reporte global “SDG Challenge” que mide la temperatura de las organizaciones a nivel mundial respecto de los Objetivos de Desarrollo Sostenible (ODS / SDG). Además, muestra los resultados de empresas chilenas, los cuales son comparados con los resultados de los ODS globales.
Independent and Joint Associations between Serum Calcium, 25-Hydroxy Vitamin D, and the Risk of Primary Liver Cancer: A Prospective Nested Case–Control Study
Authors: Yin Jian , Yin Liang-Yu , Freedman Neal D. , Li Ting-Yuan , Dawsey Sanford M. , Cui Jian-Feng , Taylor Philip R. , Liu Bin , Fan Jin-Hu , Chen Wen , Abnet Christian C. , Qiao You-Lin
Published: August 2020

Background:

Accumulating evidence has shown that serum calcium and vitamin D may be associated with or influence various cancer risks. However, no prospective studies have evaluated the independent and joint associations between prediagnostic levels of serum calcium and vitamin D and future risk of incident primary liver cancer.

Methods:

We used a nested case–control design to evaluate subjects over 22 years of follow-up. Serum calcium, 25-hydroxy vitamin D [25(OH)D], and three markers of hepatitis B virus and hepatitis C virus were measured in baseline serum from 226 incident primary liver cancer cases and 1,061 matched controls. We calculated ORs and 95% confidence intervals (CI) using logistic regression to estimate the associations between calcium, 25(OH)D, and primary liver cancer risk.

Results:

Multivariable adjusted models showed that subjects with both low (ORLow/Medium = 1.48, 95% CI = 1.01–2.17) or high (ORHigh/Medium = 1.92, 95% CI = 1.34–2.76) calcium had an increased primary liver cancer risk, while those with high 25(OH)D had a decreased risk of primary liver cancer (ORHigh/Medium = 0.54, 95% CI = 0.35–0.82). In joint analyses, when compared with subjects with medium calcium and 25(OH)D, subjects with high calcium and medium 25(OH)D had elevated odds of developing primary liver cancer (OR = 1.89, 95% CI = 1.17–3.05); those with medium calcium and high 25(OH)D had reduced odds of developing primary liver cancer (OR = 0.34, 95% CI = 0.17–0.67); and subjects in other classifications of calcium and serum 25(OH)D levels had no change in the odds of developing primary liver cancer (all P > 0.05).

Conclusions:

In a nutrient-deficient population, we found that serum calcium and serum 25(OH)D could potentially be modifiable risk or protective factors.

Impact:

Our findings provide potential targets for primary liver cancer prevention and control.
Racial Differences in Helicobacter pylori CagA Sero-prevalence in a Consortium of Adult Cohorts in the United States
Authors: Varga Matthew G. , Butt Julia , Blot William J. , Le Marchand Loïc , Haiman Christopher A. , Chen Yu , Wassertheil-Smoller Sylvia , Tinker Lesley F. , Peek Richard M. , Potter John D. , Cover Timothy L. , Hyslop Terry , Zeleniuch-Jacquotte Anne , Berndt Sonja I. , Hildesheim Allan , Waterboer Tim , Pawlita Michael , Epplein Meira
Published: August 2020

Background:

Prevalence of Helicobacter pylori (H. pylori) infection, the main risk factor for gastric cancer, has been decreasing in the United States; however, there remains a substantial racial disparity. Moreover, the time-trends for prevalence of CagA-positive H. pylori infection, the most virulent form, are unknown in the U.S. population. We sought to assess prevalence of CagA-positive H. pylori infection over time by race in the United States.

Methods:

We utilized multiplex serology to quantify antibody responses to H. pylori antigens in 4,476 participants across five cohorts that sampled adults from 1985 to 2009. Using log-binomial regression models, we calculated prevalence ratios and 95% confidence intervals for the association between H. pylori–CagA sero-prevalence and birth year by race.

Results:

African Americans were three times more likely to be H. pylori–CagA sero-positive than Whites. After adjustment, H. pylori–CagA sero-prevalence was lower with increasing birth year among Whites (Ptrend = 0.001), but remained stable for African Americans. When stratified by sex and education separately, the decline in H. pylori–CagA sero-positivity among Whites remained only for females (Ptrend < 0.001) and was independent of educational attainment. Among African Americans, there was no difference by sex; furthermore, sero-prevalence increased with increasing birth year among those with a high school education or less (P = 0.006).

Conclusions:

Among individuals in the United States born from the 1920s to 1960s, H. pylori–CagA sero-prevalence has declined among Whites, but not among African Americans.

Impact:

Our findings suggest a widening racial disparity in the prevalence of the most virulent form of H. pylori, the main cause of gastric cancer.
Pedestrian detection using Doppler radar and LSTM neural network
Authors: Azizi Mussyazwann Azizi Mustafa , Noh Mohammad Nazrin Mohd , Pasya Idnin , Yassin Ahmad Ihsan Mohd , Ali Megat Syahirul Amin Megat
Published: August 2020

Integration of radar systems as primary sensor with deep learning algorithms in driver assist systems is still limited. Its implementation would greatly help in continuous monitoring of visual blind spots from incoming pedestrians. Hence, this study proposes a single-input single-output based Doppler radar and long short-term memory (LSTM) neural network for pedestrian detection. The radar is placed in monostatic configuration at an angle of 45 degree from line of sight. Continuous wave with frequency of 1.9 GHz are continuously transmitted from the antenna. The returning signal from the approaching subjects is characterized by the branching peaks higher than the transmitted frequency. A total of 1108 spectrum traces with Doppler shifts characteristics is acquired from eight volunteers. Another 1108 spectrum traces without Doppler shifts are used for control purposes. The traces are then fed to LSTM neural network for training, validation and testing. Generally, the proposed method was able to detect pedestrian with 88.9% accuracy for training and 87.3% accuracy for testing.