bluuebunny/crossref_metadata_2025_split huggingface dataset:
GaN-based complementary inverter logic gate using InGaN/GaN superlattice capped enhancement-mode field-effect-transistors
Authors: Jha Jaya , Ganguly Swaroop , Saha Dipankar 
Published: April 2021

Abstract
GaN-based high electron mobility transistors (HEMTs) have received much attention due to their potential usage in radio-frequency and high power applications. However, the development of logic gates has remained mostly elusive due to the still challenging reliable operation of the field-effect enhancement-mode n-transistor and nascent stage for the p-transistor. The n-transistor behavior is mainly achieved by combining the aggressive thinning down of the barrier layer, using charged oxides, and p-doping the cap layer. The p-transistor generally requires a heavily doped p-GaN layer. The realization of both transistors on the same substrate remains challenging due to the conflicting requirements for n- and p-transistors. Here, we propose a GaN-based field-effect complementary transistor device using a p-doped InGaN/GaN superlattice (SL) structure on top of the barrier layer of the HEMT heterostructure. The SL structure changes the electrostatics of the heterostructure by the formation of a two-dimensional hole gas region. An undoped SL structure is shown to be enough to lift the conduction band-edge above the Fermi level to convert the n-transistor from depletion-mode (D-mode) to enhancement-mode (E-mode). The lifting of the bands, in turn, creates a natural quantum-well for the holes in the p-transistor. An additional p-doping of the SL moves the threshold voltage of the E-mode n-transistor further into a positive direction and increases the hole density in the quantum-well E-mode p-transistor. The SL structure, which can be grown by a standard epitaxial process, facilitates the realizations of both the n- and p-transistors. The characteristics of individual devices are further analyzed. A digital inverter gate is simulated, and critical static and dynamic performance parameters are reported. The propagation delay indicates that logic operations can be done at a very high speed compared to those offered by other conventional semiconductors.
Technical considerations for evaluating clinical prediction indices: a case study for predicting code blue events with MEWS
Authors: Gadhoumi Kais , Beltran Alex , Scully Christopher G , Xiao Ran , Nahmias David O , Hu Xiao 
Published: April 2021

Abstract

Objective. There have been many efforts to develop tools predictive of health deterioration in hospitalized patients, but comprehensive evaluation of their predictive ability is often lacking to guide implementation in clinical practice. In this work, we propose new techniques and metrics for evaluating the performance of predictive alert algorithms and illustrate the advantage of capturing the timeliness and the clinical burden of alerts through the example of the modified early warning score (MEWS) applied to the prediction of in-hospital code blue events. Approach. Different implementations of MEWS were calculated from available physiological parameter measurements collected from the electronic health records of ICU adult patients. The performance of MEWS was evaluated using conventional and a set of non-conventional metrics and approaches that take into account the timeliness and practicality of alarms as well as the false alarm burden. Main results. MEWS calculated using the worst-case measurement (i.e. values scoring 3 points in the MEWS definition) over 2 h intervals significantly reduced the false alarm rate by over 50% (from 0.19/h to 0.08/h) while maintaining similar sensitivity levels as MEWS calculated from raw measurements (∼80%). By considering a prediction horizon of 12 h preceding a code blue event, a significant improvement in the specificity (∼60%), the precision (∼155%), and the work-up to detection ratio (∼50%) could be achieved, at the cost of a relatively marginal decrease in sensitivity (∼10%). Significance. Performance aspects pertaining to the timeliness and burden of alarms can aid in understanding the potential utility of a predictive alarm algorithm in clinical settings.
Cyclic behavior of an adaptive seismic isolation system combining a double friction pendulum bearing and shape memory alloy cables
Authors: Peng Zhuang , Wei Wang , Yibo Li , Miao Han 
Published: April 2021

Abstract
A new composite isolator named shape memory alloy cable-double friction pendulum bearing (SCDFPB), which combines a double friction pendulum bearing (DFPB) with superelastic shape memory alloy (SMA) cables, is proposed. Based on the SMA cables, the proposed isolation bearing named as SCDFPB had capability to adapt to multi-level earthquake intensities in horizontal directions, which was superior to the conventional DFPB. A series of research was performed to investigate hysteretic behavior of the SCDFPB, and a numerical simulation method for this isolation device was also developed. First, the configuration design and operation principle of the SCDFPB were described and explained in detail. Then, an analytical model of SCDFPBs was presented to understand their control and energy dissipation properties. Next, a SCDFPB specimen was designed and fabricated, and the quasi-static tests on the isolator specimen under different loading conditions were conducted to examine the isolator’s real cyclic response. The influence of displacement amplitude, vertical load and loading frequency on the hysteretic performance of SCDFPB specimen was investigated, and the behaviors of SCDFPB were compared with those of DFPB. Theoretical analyses were also performed to trace the vertical and horizontal components of the force provided by the SMA cables and their influence on the overall response of the entire isolation system during the cyclic loading process of the SCDFPB specimen. Finally, a numerical model of the SCDFPB implemented in the OpenSees program was established and validated by comparison to the experimental results.
Cooperation and dependencies in multipartite systems
Authors: Kłobus Waldemar , Miller Marek , Pandit Mahasweta , Ganardi Ray , Knips Lukas , Dziewior Jan , Meinecke Jasmin , Weinfurter Harald , Laskowski Wiesław , Paterek Tomasz 
Published: April 2021

Abstract
We propose an information-theoretic quantifier for the advantage gained from cooperation that captures the degree of dependency between subsystems of a global system. The quantifier is distinct from measures of multipartite correlations despite sharing many properties with them. It is directly computable for classical as well as quantum systems and reduces to comparing the respective conditional mutual information between any two subsystems. Exemplarily we show the benefits of using the new quantifier for symmetric quantum secret sharing. We also prove an inequality characterizing the lack of monotonicity of conditional mutual information under local operations and provide intuitive understanding for it. This underlines the distinction between the multipartite dependence measure introduced here and multipartite correlations.
Polarization of GRB prompt emission and its application to POLAR’s data
Authors: Lan Mi-Xiang , Wu Xue-Feng , Dai Zi-Gao 
Published: April 2021

AbstractSynchrotron emission polarization is very sensitive to the magnetic field configuration. Recently, polarization of synchrotron emission with a mixed (SM) magnetic field in the gamma-ray burst (GRB) afterglow phase has been developed. Here, we apply these SM models to the GRB prompt phase and compare their polarization properties with that of synchrotron emission in purely ordered (SO) magnetic field. We find that the polarization properties in an SM model are very similar to these in a corresponding SO model (e.g., synchrotron emission in a mixed magnetic field with an aligned ordered part (SMA) and synchrotron emission with a purely ordered aligned magnetic field (SOA)), only with a lower polarization degree (PD). We also discuss the statistical properties of the models. We find PDs of the simulated bursts are concentrated around 25% for both SOA and synchrotron emission in a purely ordered toroidal magnetic field (SOT), while they can range from 0% to 25% for SMA and synchrotron emission in a mixed magnetic field with a toroidal ordered part (SMT), depending onξBvalue, i.e., the ratio of magnetic reduction of the ordered magnetic field over that of random magnetic field. From statistics, if PDs of majority GRBs are non-zero, then it favors SO and SM models. Further, if there are some bright GRBs with prominently lower PDs than that of the majority GRBs, it favors SOT (SMT) models; if all the bright GRBs have comparable PDs with the majority ones, it favors SOA (SMA) models. Finally, we apply our results to POLAR’s data and find that ∼ 10% time-integrated PDs of the observed bursts favor SMA and SMT models, and theξBparameter of these bursts is constrained to be around 1.135.
Detection of a high-confidence quasi-periodic oscillation in radio light curve of the high redshift FSRQ PKS J0805–0111
Authors: Ren Guo-Wei , Zhang Hao-Jing , Zhang Xiong , Ding Nan , Yang Xing , Li Fu-Ting , Yan Pei-Lin , Xu Xiao-Lin 
Published: April 2021

Abstract
In this work, we have searched for quasi-periodic oscillations (QPOs) in the 15 GHz light curve of the FSRQ PKS J0805--0111 monitored by the Owens Valley Radio Observatory (OVRO) 40 m telescope during the period from 2008 January 9 to 2019 May 9, using the weighted wavelet Z-transform (WWZ) and the Lomb-Scargle Periodogram (LSP) techniques. This is the first time to search for a periodic radio signal in the FSRQ PKS J0805–0111 by these two methods. Both methods consistently reveal a repeating signal with a periodicity of 3.38 ± 0.8 yr (>99.7% confidence level). In order to determine the significance of the periods, the false alarm probability method was applied, and a large number of Monte Carlo simulations were performed. As possible explanations, we discuss a number of scenarios including the thermal instability of thin disks scenario, the spiral jet scenario and the binary supermassive black hole scenario. We expect that the binary black hole scenario, where the QPO is caused by the precession of binary black holes, is the most likely explanation. FSRQ PKS J0805-0111 thus could be a good binary black hole candidate. In the binary black hole scenario, the distance between the primary black hole and the secondary black hole is about 1.71 × 1016 cm.
Measurement of Hubble constant: were differences in secondary distance indicators apparent as early as the HST Key Project?
Authors: Thakur Rahul Kumar , Gupta Shashikant , Nigam Rahul , Thiruvikraman PK 
Published: April 2021

Abstract
Different measurements of the Hubble constant (H
0) are not consistent, and a tension between the CMB based methods and cosmic distance ladder based methods has been observed. Measurements from various distance based methods are also inconsistent. To aggravate the problem, the same cosmological probe (Type Ia SNe for instance) calibrated through different methods also provides different values of H
0. We compare various distance ladder based methods through the already available unique data obtained from the Hubble Space Telescope (HST). Our analysis is based on parametric (t-test) as well as non-parametric statistical methods such as the Mann-Whitney U test and Kolmogorov-Smirnov test. Our results show that different methods provide different values of H
0 and the differences are statistically significant. The biases in the calibration would not account for these differences as the data have been taken from a single telescope with a common calibration scheme. The unknown physical effects or issues with the empirical relations of distance measurement from different probes could give rise to these differences.
Possible properties of TeV spectra in PKS 2155–304
Authors: Gao Quan-Gui , Lu Fang-Wu , Qin Long-Hua , Li Huai-Zhen , Ma Ju , Ren Ji-Yang , Zhao Hai-Ru , Yi Ting-Feng 
Published: April 2021

Abstract
We present a one-zone homogeneous lepton-hadronic model and obtain steady-state spectra by solving the time-dependent equations to study a plausible origin of hard TeV spectra in PKS 2155–304. In this model, we assume a steady electron and proton injection rate in the source and solve the non-linear time-dependent kinematic equations that self-consistently consist of proton-photon interaction, synchrotron radiation of electron/positron pairs and proton, inverse Compton scattering, and synchrotron self-absorption. We employ this model to reproduce the multi-wavelength spectrum of PKS 2155–304, then find that the possible bump located at E ∼ 1 TeV which may originate from the synchrotron radiation of secondary electrons produced by Bethe-Heitler pair production, resulting in the hard TeV spectrum.
Development of a solar energy-powered surface water pump
Authors: Agbo S , Samuel O.D. , Amosun S.T. , Oyejide O.J. , Fayomi O.S.I. , Bamisaye O.S. , Afolalu S.A. 
Published: April 2021

Abstract
Availability in energy and water sustainability are mounting concerns in several parts of the world where connection to the electric utility is not obtainable or irregular. There is a need to develop an alternative source of energy for pumping water. This research developed a solar energy powered 1.5 horsepower surface water pump. It comprises of the following major components: charge controller, 24 Volts DC battery, 3KVA inverter, solar panel and 1119W surface water pumping machine. The components were designed and assembled according to functions. Solar energy is used to charge the battery through solar controller. The solar charge controller used in this research was designed in such a way that it regulates the quantity of electrical energy that is stored in the battery which prevents overcharging, thereby ensuring no reduction in life span of the battery. The inverter was designed in such a way that when there is no alternative power supply from the electricity distribution company, that is, power holding company of Nigeria (PHCN), it can make use of the energy stored in the battery to power the single phase motor used to pump water into a tank. Similarly, when there is power supply from PHCN, it has an inbuilt change over switch (relay) to connect it’s output of 220 volts AC supply from PHCN used to charge a battery through a charge controller. Experiments were setup to analyze varying loads on the inverter. Average time obtained for varying loads of 0, 120, 500, 1000, 1300w are 200, 23, 9.8, 4.3 and 2.9hr. Comparisons were also made between locally built and imported inverters. It can be concluded from the results obtained that the design can best be put in use to obtain maximum efficiency of 88.2% at a load in the range of 1000–1300 watts.
Prospective of Product Development and Improved Production Processes
Authors: Fayomi O.S.I. , Akande I.G. , Oyedepo S.O. , Dunmade I. , Aikhuele D.O. , Ighravwe D.E. 
Published: April 2021

Abstract
Product development is an integral part of an organization that plans to stay relevant and competitive in today’s world. Several companies have research and development sections, which are most times responsible for developing new products. Still, there are other processes such as technology development, technology acquisition, capacity acquisition, and project management in which product development can be achieved. Improved product development processes such as lean manufacturing, six sigma, and a hybrid of the two known as lean six sigma (LSS) are platforms that enhance product development, which helps organizations remain relevant.
Reinforcement of AA1237 with Al2O3 to form Metal Matrix Composite
Authors: Babalola P.O. , Kilanko O. , Banjo S.O. , Ogulu J.O. , Makinde A. , Jolayemi J.K. , Ayara W.A. 
Published: April 2021

Abstract
The fabrication of advanced materials which possess an array of desired properties is a significant accomplishment of humanity. Composites are described as enhanced materials as they possess various advantages over conventional materials, which is why these composite materials are seen as viable alternatives in diverse engineering fields such as the aerospace, electronics and automobile industries. This work involved the fabrication of a metallic composite with the use of aluminium (AA1237) and crushed Al2O3 ceramic particles of 150nm and 600nm sizes as the reinforcement. The manufacturing of these composite samples was accomplished using the liquid phase process of stir casting, and they were subjected to various mechanical and electrical tests. For both hardness and tensile tests, the specimen Al/Al2O3/10p/150nm ( 10 per cent) had the highest values with 14.9 HBS and 124.41 MPa respectively. The electrical conductivity test affirmed the presence of non-conductive ceramic particles in the composite samples as the control (AA1237) had the highest conductivity value.
Fractal Dimension Analysis of Ternary Blends Structure: Polypropylene/Chitosan/Sisal Fiber Membranes
Authors: Mokrani T. , Agboola O. , Fayomi O.S.I. , Ayeni A.O. , Ayoola A. 
Published: April 2021

Abstract
Generally, the microstructures of thin and dense skin membranes have a disorderly nature. Due to their extremely complex nature, it is necessary to study the relationship between surface morphology and fractal dimension of microfiltration membrane. The fractal dimension analysis of the polymer composite was study to provide information about the primary pore size and their associations with flux in porous media. The fractal dimensions of membranes were obtained by the box-counting method. The membranes with increased amount of sisal fiber have inter-twined fibrous network with larger pores. The fractal dimension values of the membranes were also high with increasing amount of sisal fiber, with 86%PP/10% SF/4% C having the highest value of 1.9951.
A Review of the Impact of Construction Automation and Robotics on Project Delivery
Authors: Akinradewo O I , Aigbavboa C O , Okafor C C , Oke A E , Thwala D W 
Published: April 2021

Abstract
The use of construction technologies is to improve working conditions, improve health and safety, scheduling and improving quality of the construction products. Construction automation redefines construction with machines and advanced technology to mitigate the problems faced in construction, such as labour-related issues among others. To adequately understand the impact of automation and robotics in the construction industry, this study is aimed at reviewing extant literature on how automation and robotics can be put into use in the construction industry as it is being used in the manufacturing industry. The study employed a systematic literature review approach and sourced for published journal and conference articles from Web of Science and Scopus databases. The review revealed that construction automation and robotics increase accuracy of components’ dimension through the use of lasers for dimension analysis, promote design specifications through the use of computer aided designs, increase quality of construction products by ensuring standards are met, brings cost effectiveness as value for money spent is achieved, eliminate material wastage due to accurate and precise estimate of materials needed, reduce construction accidents due to the usage of machines for dangerous construction activities, improve working condition as workers’ are more secure and safety is guaranteed, and reduce labour cost given the fact that machines are deployed for construction activities.
Effect of Fibre Glass Addition on the Mechanical Properties of Glass Fibre Reinforced Polymer (GFRP) Composite
Authors: Udo Mfon , Babalola Philip , Ongbali Samson , Banjo Solomon , Obasa Victoria , Adelore Jesutoni 
Published: April 2021

Abstract
A fibre glass reinforced polymer was developed, using epoxy resin as the matrix material and E-glass fibre as the reinforcement, by hand laying method. Different set of the composite were produced by varying the weight percentage (wt%) addition of the reinforcement to the epoxy resin as follows 10%, 20%, 30%, 40% and 50%. The polymeric composite so produced were subjected to various mechanical property tests as hardness, tensile, impact, tests. The hardness test was conducted using TQ SM1000 Universal Testing Machine, the tensile strength test was carried out on Hounsfield Tensiometer model while the impact test was carried out on Izod Impact Testing Machine. It was observed that the mechanical properties of hardness, tensile strength and impact strength were of higher values in the composites with different weight fractions of glass fibre than in unreinforced epoxy resin. It was also found out that the values of those mechanical properties increased directly proportional to the amount of weight percentage of the reinforcement in the composites with the highest of the values residing in the composite with 50 wt% of the reinforcement. The hardness value for GFRP composite with 50 wt% glass fibre reinforcement stood at 57 BHN, tensile strength at 332.7 MPa and impact energy value of 17.5 J/m2.
Corrosion and Protection of Facilities and Infrastructures in Telecommunications Industry - A Review
Authors: Loto Roland T. , Loto Cleophas A. 
Published: April 2021

AbstractA review of corrosion and protection of telecommunications facilities and infrastructures is reported here. The article gives a brief insight into the broad aspects of basic corrosion and telecommunications engineering and technology. These areas of discussion include all telecommunications metallic materials and equipment, buildings, and masts/towers. The review also discussed various corrosion protection methods such as organic/inorganic coatings, hot dip galvanizing, electroplating and electroless plating, cathodic protection, materials selection and systems design. The protection level for different components of the tower to which cathodic protection is used includes tower base, foundation of telecommunication shelters, buried portion of waveguide bridges, anchor shafts, and grounding system which were briefly discussed.
Experimental Investigation of Welding Parameters and Simulation of Heat and Fluid Flow in Weldments
Authors: Egole C.P. , Nzebuka G.C. , Anaele J.U. , Ukonu D.C. 
Published: April 2021

Abstract
Welding is one of the most versatile processes for joining components in the industrial and manufacturing sectors. Hence, the critical study of welding parameters and the heat and fluid flow behaviour is deemed necessary. In the current work, an experimental investigation of the effect of welding parameters on the mechanical properties of the welded joints and simulation of heat and fluid flow within the weldments were presented. Low carbon steel was welded using a shielded metal arc welding process (SMAW) and a single V-grooved butt joint was produced. Welding currents of 100 amperes and 115 amperes were varied for different electrode types of E 6013 (ENL), E 6013 (AWS) and E 7018 for the welding process. Tensile and hardness tests were carried out on the welded joints. X-ray diffraction analysis was carried out to ascertain the phases present within the weld area. Additionally, the heat and fluid flow patterns within the weld pool were studied using ANSYS Fluent. The results show that there are significant effects of welding current and electrode type on the tensile strength and hardness of the weldment. For all the samples analysed, electrode type rather increase in current improved the mechanical properties significantly. The optimum tensile strength for the SMAW process was produced by the welding electrode E 7018 at 115 A with a strength of 652 MPa. The lowest value of tensile strength was 491 MPa for E 6013 (AWS). The highest hardness was produced by E 7018 electrode at 115 A with a value of 177 HV while the lowest was 122 HV for E 6013 (AWS) electrode. Heat transfer analysis showed that the maximum temperature value of 1867 K was obtained close to the arc region. Due to the narrow area of weld pool occasioned by large thermal gradient and rapid solidification, the fluid flow region reported was small and the supposed recirculating flow cells and loops were not well developed.