bluuebunny/crossref_metadata_2025 huggingface dataset:
Review of internet of things: distributed power in smart grid
Authors: B M Nandish , Pushparajesh V
Published: February 2021

Emerging technologies in the field of power sector are Artificial Intelligence and Information Technology. Electrical network is very complex and Far-reaching, the data that coming from the generation, transmission or from the distribution is abundant and needs to be processed for better efficiency and reliability. To achieve higher efficiency power grids are incorporating newer technologies and are adapting. Internet of Thing (IOT) is a modernized technology that can be used to collect the data or to monitor the physical components under the radar of the grids. This paper deliberates the use of modern technology in the smart grids to improvise the reliability and working efficiency. The concept of Distributed generation and the utilization of IOT in such scenario is discussed in this paper.
FFNN BASED MPPT CONTROLLER FOR PEMFC POWERED NON-ISOLATED HIGH GAIN DC-DC CONVERTER WITH SPWM INVERTER FED BLDC MOTOR
Authors: Karthikeyan B. , Kalyanasundaram V. , Vidyasagar S. , Sundararaju K. , Palanisamy R.
Published: February 2021

A Non-Isolated High Gain DC-DC converter fed from 1.2kW PEMFC is designed to boost the fuel cell voltage. The Feed-forward Neural Network based MPPT controller algorithm is implemented to adjust the duty cycle of DC-DC converter in order make sure optimum power extraction from PEMFC whose result is compared with Fuzzy Logic Controller. The boosted DC voltage is inverteted to drive BLDC motor by three phase inverter. The inverter switches are triggered with switching pattern generated by SPWM technique according to the Hall sensor signals placed at stator of BLDC motor to find the position of rotor. The simulation anlysis has been carried out using MATLAB (R2017a)/Simulink platform and discussed the results.
Multilayer electromagnetic wave absorber by a dielectric material in direct to home system
Authors: Snega S , Narmadha K , Yuvashree R , Arunkumar M , Dhanasekar R , Vijayaraja L , Kesavan Rupa
Published: February 2021

The satellite is the one which plays a vital role in the medium of satellite dishes for television, communication, internet and most important role in military application. The solution for this problem occur in the satellite dish used for television is discussed here. Whenever the development is done by taking the technology as medium and smart innovative work are done, at last it has some disadvantage which finally occurs as a problem that is changes in meteorological conditions leads to disconnection of the signal. Although a renowned parabolic reflector is there, it gets shattered before reaching the receiver due to the cold rain weather condition. The method and material proposed here will be able to overcome the problem occurred.
Design of off-grid solar photovoltaic system using DC-DC topologies for BIUST classrooms
Authors: Tlhabologo B A , Molosiwa G , Ongadile O , Samikannu Ravi
Published: February 2021

The project is to Design and Develop an OFF-GRID solar photovoltaic System using DC-DC Topologies for BIUST classrooms light loads (lighting, projector, and computer). Narrowing this topic, focus is on harvesting solar energy using photovoltaic cells then boost the power using a DC-DC boost converter. This project consists of different subsystems, which are combined to have the solar system for classrooms light loads. These are Photovoltaic Solar Array, Maximum Power Point Tracking (MPPT), DC-DC boost converter and battery bank stores energy to be used when the sunrays are not efficient to supply the load. Lastly a DC-to-AC inverter is designed. The system is design is based on performed calculation to size each component to keep the system efficiency high. According to simulation of different DC-DC converters using Simulink, boost was the best converter to use looking at the output characteristics desired. Results from Proteus software simulation of the final circuit correspond with expectation from literature review. Furthermore, PVsyst software has been used to do the mathematical analysis of the designed model showing an estimated payback period of 2.6years whereas the output power for PVsyst model is 11.9 kW which the system produces given the design parameters calculated.
Augmentation of Low Voltage Ride through (LVRT) Capability using ANN based electric spring for a Grid-tied Wind Energy Conversion System
Authors: Udayakumar M.D. , Saradha Devi A. , Raja E. , Nazar Ali A , Stonier Albert Alexander
Published: February 2021

Electric Spring (ES) is an innovative approach for distributed voltage control (DVC) whereas at the same time accomplishing nominal demand-side management (DSM) technique for continuously varying renewable energy sources. In order to demonstrate the efficiency of ES when deployed in enormous quantities across the grid-connected power distribution system, it is important to build easy and reliable simulation models of ES that can be integrated into large-scale simulation studies of the power system. The ES study gap identification method defines the ES dynamic simulation methodology that is appropriate for the WECS grid-connected voltage and frequency control studies. The integration of WECS to the electric grid leads to many serious power quality problems. Low voltage ride through (LVRT) capability improvement is one of the important constraints in grid connected WECS. This articleexamines the enhancement of LVRT capability of Doubly Fed Induction Generator (DFIG) based grid connected WECS by usingES. The effectiveness of proposed Artificial Neural Network (ANN) based Electric spring controller is compared with existing PI controller using MATLAB/Simulink software. It is evident that the proposed controller nurtures the trustworthiness of WECS when integrated with existing electric power grid system.
Design and development of microcontroller-based temperature monitoring and control system for power plant generators
Authors: Ponnusamy Sukumar , Samikannu Ravi , Tlhabologo B A , Ullah W , Murugesan Srinivasan
Published: February 2021

The protection of turbine generator systems is an important factor that must be considered in power plant for efficient production of electricity. This project deals with temperature level monitoring of the power generator and it will be compared with the predetermined standard value through an LM35 sensor. Once it exceeds the predetermined value then the cooling fan will automatically turn on which will be useful to prevent the generator from internal winding thermal failure. The protection system consists of 16x2 LCD display, LM35 temperature sensor, a coolant fan and a microcontroller [ATMEGA328P]. The internal winding temperature of generator is increased as the turbine is rotated at its axis which may lead to major damages in the axial position and shafts of the power generator. To overcome this, an LM35 sensor is connected and linked with the microcontroller which monitors the temperature and once it exceeds the standard temperature the coolant fan automatically is turned on by the microcontroller and the heat of the steam will be countered by the cooling air produced by the coolant fan. The fan runs continuously until the temperature is sensed to have dropped below the standard temperature. At the same instances, the LCD display outputs readable current temperature parameters for the operator. The protection of power generator system is a vital component in power plant for efficient production of electricity.
Experimental Investigation of Air Circulation Using Duct System in a Non-AC Bus Coach
Authors: Niranjana SJ , Kubsad Shivalingappa S , Nagaraj Y , Manjunath S , Shivakumar S
Published: February 2021

Public transport is the life line in many of the developing and under developed countries for the safe conveyance, i.e. also consider as economical. The major limitation in public transport (non-AC busses) Air Condition, is the lack of proper air circulation leading to suffocation and vomiting. The present research work emphasis on design and analysis of air flow duct system (non AC Busses) to increase the level of comfortance of the passengers, tools like solidworks software 2016 is used for 3D drawing, Hypermesh software 13.0 is for the discretization and ANSYS Fluent software 16.0 for the Computational Fluid Dynamic (CFD) analysis, from the experimental the airflow is found to be 10 m/s, and from the numerical analysis the airflow is found to be 9.8 m/s, by comparing the experimental and numerical results a negligible deviation of 2% is observed and it is within the limit.
Immobilization of copper sulfide flotation tailings through the use of geopolymers, Tacna – Perú.
Authors: Morales-Aranibar C , Linares-Gutiérrez N , Morales-Aranibar L
Published: February 2021

Currently, mining-metallurgical industrial activities generate significant amounts of mining tailings, and innovative environmentally friendly methods are required for their final disposal or sustainable immobilization. The objective of the study was to immobilize copper sulphide flotation tailings through the geopolymerization process. The samples were obtained from the Toquepala mining unit, - Tacna (Peru), the ash from the ENGIE-Moquegua hydroelectric plant. The results in the first phase of the characterization of the ash (FA) and the mining tailings (MT) through the chemical analysis EDX, mineralogical DRX and morphological SEM, show aluminosilicate content, in the second phase the mixtures of 55% MT, 37, 5% FA and 7.5% MK activated at 10 M at 35 days of curing, demonstrated resistance of 24.6 Mpa according to mechanical resistance tests, the mixture of 100% MT activated at 10 M at 35 days of curing, it is effective by itself for the formation of the geopolymer, obtaining resistances of 22.68 Mpa, the SEM analysis demonstrated formation of tetragonal structures typical of a geopolymer, the TCLP analysis demonstrated a significant reduction of the contaminating elements Ba, Cd, Cr, Pb, opening a new field for tailings treatment.
Design of a fixture for single incremental forming (SPIF) process based on design for assembly (DFA) methods
Authors: Al-Hafiz Abdul Razak Kamarul , Baharuddin Abdullah Ahmad , Samad Zahurin , Farizuan Muhammad Fauzi Muhammad
Published: February 2021

This paper discusses the application of Design for Assembly (DFA) Method, Boothroyd Dewhurst to select the best design of a fixture for Single Point Incremental Forming (SPIF). The 3D design of fixtures was created using SOLIDWORKS 2016 software. This research will focus on the manual handling and insertion of the fixtures by reducing the number of parts and comparing between two designed fixtures. The chosen design has been made based on the best design efficiency. The result found that the application of DFA improved the design efficiency, where welded-based Design B is 35.62% greater than design efficiency of fastener-based fixture Design A which is 23.04%.
Study of wear performance of crosslinking UHMWPE acetabular liner for artificial hip joint made from CNC milling
Authors: Lestari W D , Nugroho A , Ismail R , Jamari J , Bayuseno A P
Published: February 2021

Crosslinked ultra-high molecular weight polyethylene (UHMWPE) is a preferred material used as a bearing material in the artificial hip joint. The purpose of this study was to analyze the effect of dose cross-linking acetabular liner manufactured by CNC milling on wear depth. The wear test is carried out with a tribometer machine by loading the acetabular liner in a certain cycle. The test results found that specimens given a crosslink dose of 50 kGy with a load of 800 N resulted in a greater wear depth compared to specimens given a crosslink dose of 100 kGy with a load of 800 N. Specimen with crosslink dose 50 kGy yield greater wear depth than specimens given a crosslink dose of 100 kGy. Based on these results it can be concluded that the greater the crosslink dose given to the specimen will increase the wear resistance of the specimen so that the test results in a smaller wear depth.
Hydrogen fuel cells for sustainable energy: Development and progress in selected developed countries
Authors: Baharuddin N A , Wan Yusoff W N A , Abd Aziz A J , Mohd Tahir N N
Published: February 2021

The sustainable development goals concept towards zero carbon emission, set forth by the Paris Agreement, is the foundation of decarbonisation implemented in most developed countries worldwide. One of the efforts in the decarbonisation of the environment is through hydrogen fuel cell technology. A fuel cell is an energy converter device that produces electricity via the electrochemical reaction, with water as the by-product. The application of fuel cells is strongly related to the economic aspect, including local and infrastructure costs, making it more relevant to be implemented in a developed country. This work presents a short review of the development and progress of hydrogen fuel cells in a developed country such as Japan, Germany, USA, Denmark, and China (in transition between developing to developed status); which championed hydrogen fuel cell technology in their region.
Suction effect on an unsteady Casson hybrid nanofluid film past a stretching sheet with heat transfer analysis
Authors: Ilyana Kamis Nur , Md Basir Md Faisal , Shafie Sharidan , Khairi Ahmad Khairuddin Taufiq , Yeou Jiann Lim
Published: February 2021

This paper studies the heat transfer in the blood fluid-based copper and alumina nanoparticles over an unsteady permeable stretching sheet. The model is governed by the governing equations consist of a series of ODEs that are reduced from PDEs by implementing the similarity transformations subjected to mixed boundary conditions. The results of the transformed equations has been obtained by using the Keller-box method in MATLAB software. This paper focuses on the characteristics of thin-film flow and heat transfer through the governing parameters; unsteadiness parameter, nanoparticles volume fraction, Casson parameter, and intensity of suction. From this study, it is observed that the behavior of both fields for nanofluid is lower than hybrid nanofluid under the suction effect. It is noticed that enhance the physical parameters increase the velocity field of the fluid. Further, increase the physical parameter also deteriorate the temperature field except for nanoparticles volume fraction.
Investigation of design space in manufacturing meta-biomaterials by additive manufacturing
Authors: Rohaida Mohamed Siti , Anwar Che Ghani Saiful
Published: February 2021

Topology features such as interconnectivity, pore shape and size, porosity, struts thickness, and used materials play the key roles for mechanical and biological properties of meta-biomaterials structures. However, the influences of morphological geometries on the mechanical and biological properties are not certainly intuitive. This paper develops parametric model that use to visualize the morphological geometries of unit cell of meta-biomaterials on design space that governing the manufacturing limitation, mechanical and biological requirements. The selected samples within design spaces tested to determine manufacturing accuracy and effective elastic modulus by finite element analysis. The geometries discrepancies between designed models and manufactured samples obtained percentage of average errors of 13% for diamonds structures and 21% for square structures. The proposed technique yielded average error reduced to 74.4% for diamond structures and 44.4% for square structures of effective elastic modulus from theoretical calculation. The approach and the implications of the results discussed in the context of mechanical and biological criteria with highlight of advantages and limitations of meta-biomaterials manufactured by additive manufacturing for orthopaedic implants.
The effect of quick response manufacturing in factory layout: Assessment using Witness software
Authors: Yusoof M Y M , Mohamed N M Z N , Nelfiyanti  , Hadi M Z I A
Published: February 2021

Nowadays, in a new era of industrial revolution 4.0, there are still many manufacturing companies that tend to neglect the knowledge of optimizing the factory layout. By doing so, the productivity can be increase and lessen the burden of the operator while making sure the quality and also the number of products are also at optimum. The objective of this study is to conduct an analysis on the actual arrangement assembly line using witness software based on QRM in V model assembly and also to propose a new arrangement of the assembly line using Witness software. The data has been collected and recorded through some observation during the visit to X Company. The current layout of the V model assembly line is simulated in the Witness software to get its actual process, percentage of idle, and also the setup time. The software is also used for the new improvement of the assembly line layout to get the comparison for the current layout and after the improvement. Based on the current result, there is some station that has a high percentage of blockage occur in the layout and after the improvement, the percentage of blockage has been reduced which help in increase the production of the model per day. The data that has been recorded from the current is compared with the data after the improvement has been made to the assembly line.
Various risks and safety analysis to reduce fire in oil refinery plant
Authors: Alam Md Zahangir , Sakib Md Nazmus , Islam Minarul , Jalal Uddin Mohammad
Published: February 2021

It is quite hazardous to produce the final product of oil or gas in a petrochemical refinery plant due to its flammable or combustible and explosive materials. Small mistakes can cause massive damage to life, property, pollution, injury, ecosystem, and business by fire. The entire system is challenging to manage. Therefore, fire risk assessment and forecasting are necessary to overcome personal, environmental, and refinery plants’ hazard situations. There have been four main threats in any refinery facility: electrical, mechanical, civil, and chemical issues, maximum cases its result burning. This research aimed to study and assess fire risk in the refinery plant by using a multi-stage early warning system and reducing the fire. The fire hazard safety layer technique would be used for our petrochemical process. Some equipment is set in place to forecast the danger and execution before and after it happens. Geographic information systems (GIS), remote sensing (RS) are some techniques for fire incidents tracking. Flame detectors, heat detectors, and gas detectors are used to maintain good contact in the entire risk analyzer portion. Various techniques and monitoring have been proposed to operate the plant efficiently and safely, like controlling, predicting, and pre-warning strategic planning.
A review of FDM and graphene-based polymer composite
Authors: Mogan J , Sandanamsamy L , Halim N A , Harun W S W , Kadirgama K , Ramasamy D
Published: February 2021

Graphene is a carbon that has a unique structure that is excellent in enhancing mechanical, electrical and thermal properties. The fused deposition modelling (FDM) process is a widely used 3D printing method for its low investment and operating cost. Although the FDM process is cheaper and affordable, yet the printed parts are more fragile compare to other 3D printing methods. This paper covers about FDM process and the type of base materials and filler materials. However, the focus is mainly on ABS and graphene. The mechanical properties of ABS/Graphene polymer composite and application of ABS and graphene in the industry were also discussed. Hence, it proved that graphene enhances the properties of ABS. This study is done to improve polymer-based filaments for future references.
Review on thermal energy storage and eutectic nitrate salt melting point
Authors: Samylingam I , Kadirgama K , Aslfattahi Navid , Samylingam L , Ramasamy D , Harun W S W , Samykano M , Saidur R
Published: February 2021

In solar concentrates, thermal energy (TES) storage has a significant function (CSP). This article will discuss the forms of TES and TES content, focusing on the material for latent heat storage. Sensitive heat storage, latent heat storage and chemical reaction thermal storage classes can divide TES into three classes. Among the thermophysical properties for CSP is the latent heat storage content, which is used by more researchers. Dividing latent heat storage material into material for the organic, inorganic and eutetic phases change material (PCM). There are an advantage and downside to any form of storage material. Thermal stability at high temperature and low cost, however the specific heat capacity of the sensible heat storage material is very low compared to the latent heat storage materials..
Heat transfer analysis in compact heat exchanger with fibre reinforced plate
Authors: Hamood M , Oumer A N , Abd Aziz Azizuddin , Ishak M , Siregar J P , Mamat O
Published: February 2021

Due to their lightweight and ease of manufacturing, fibre-reinforced composites are replacing metals in many heat exchanger applications. However, their heat transfer dissipation performance is not investigated in detail. This paper aims to study experimentally the heat transfer performance of fins made from fibre reinforced composites in compact heat exchangers. Thin fins were manufactured from reinforced fibre composites by the hot pressing technique. The fins have dimensions of 11.5 cm wide and 11.5 cm long. Five different airflow velocities with fixed water flow rates were considered in the analysis. The temperature distribution inside the tube was measured at eight different points using a K-type thermocouple.

The results showed that the water temperature at the outlet section was the highest at the lowest airflow velocity. Moreover, the air-side heat transfer coefficient increased along the tube length at all airflow velocities. The comparable heat transfer performance results make the fibre reinforced fins a good choice in the compact fin-and-tube heat exchanger.
Laser cladding process to enhanced surface properties of hot press forming die: A review
Authors: Norhafzan B , Khairil C M , Aqida S N
Published: February 2021

Laser cladding is one of the advance processes in laser surface treatments. The process involved a laser beam to combines another material that has different metallurgical properties on a substrate, whereby a very thin layer of the substrate has to be melted for it to achieve metallurgical bonding with minimal dilution of added material and substrate. The resulted properties were characterized by surface topography, subsurface microstructure, hardness, and residual stresses. The objective of this paper is to review the factors that affected of cladding process to get the best cladding, suitable to enhance hot press forming die surface and subsurface. The parameter control, metallurgical bonding between coating and substrate, and effect of powder size were discussed.
Multilayer Huygens’ metasurface absorber toward snapshot multispectral imaging
Authors: Wen Shun , Jin Chunqi , Yang Yuanmu
Published: February 2021

Multispectral or hyperspectral imaging requires the collection of a three-dimensional (3D) data cube that is composed of 2D spatial information and 1D spectral information of the scene. However, conventional cameras can only record 2D information, such that to obtain the 3D data cube, one needs to sacrifice either spatial or spectral resolution, or spatial or spectral scanning is required. Here, we introduce a multilayer metasurface absorber platform that may potentially allow the collection of a multispectral data cube in a single shot, without sacrificing the resolution. We design each absorber layer composed of silicon nano-resonators to support a Huygens’ mode in the visible spectrum, such that each layer may detect an impinging scene only within a narrow spectral band. We envision that the multilayer metasurface absorber, if integrated with proper electronics, may be used for snapshot multispectral imaging, with potential applications in target identification with high spatial and spectral resolution.
Dielectric breakdown properties of Al-air mixtures
Authors: CAI Xiyuan , ZHANG Xiao , LU Junyong , TAN Sai , ZHANG Yongsheng , ZHANG Guanxiang
Published: February 2021

In order to investigate the influence of aluminum vapor on the breakdown performance of air, this paper makes a study of the dielectric breakdown characteristics of Al-air mixture in the temperature range of 300–5000 K at atmospheric pressure. A Boltzmann analysis method is used to deal with the electron energy distribution function (EEDF), the reduced ionization coefficients (α/N), the reduced attachment coefficients (η/N) and the critical reduced breakdown strength ((E/N)cr) so as to explore the influence of temperature and mixing ratio on the dielectric breakdown properties. In the temperature range of 300–2000 K, the property of the mixture is mainly determined by the mixing proportion of aluminum vapor because the composition of particles remains unchanged. In the temperature range of 2000–2500 K, the decomposition of Al2O2 leads to the increase of aluminum oxides and NO, and a rise in the percentage of high-energy electrons as well as the increment of α/N. Also, the joint action of O2 and NO makes η/N increase first and then decrease, and (E/N)cr goes down to a smaller temperature range. An increase in the proportion of aluminum vapor causes (E/N)cr to decrease in the low-temperature region and to increase in the high-temperature region, which will reduce the transition between these two temperature regions.
Long-time oscillations in correlation of lysozyme solutions and the effects of antagonistic salt in external electric field light scattering
Authors: Kang Kyongok , Sadakane Koichiro
Published: February 2021

Lysozyme is a ubiquitous protein and enzyme that prevents the bacterial infections and maintains the catalytic balance in majority of biological fluids. However, it often causes problems at higher concentrations. In particular, the build up of lysozyme engaged with other protein interactions initiates severe disorders in most mammalian cells, such as the formation of harmful aggregates in the nervous system and the loss of connectivity in rheumatism. To understand such complex behaviors with respective to the catalytic activity of the enzyme, the lysozyme solution and the effect of hydrophobic antagonistic salt (NaBPh4) are explored in-vitro, in their relaxation behaviors. Here, we used, both normal dynamic light scattering and home-built in situ AC external electric field light scattering. As results, the fast and slow-mode (with stretched) relaxations are observed in the conventional dynamic light scattering (without an electric field). The results are particularly noteworthy under a low electric field, with robust long-time oscillations, in the scattered intensity correlation function. In addition, the effective interactions are explored by varying the ionic strength of the antagonistic salt: The oscillations are less pronounced, but still clearly represent the ‘underdamped’ motions. Overall, reductions of the relaxations are shown with the applied electric field, with a maximum relaxation occuring at 1mM. In contrast, monotonic decreases of the relaxation rates are shown above 10 mM. Thus, the lysozyme exhibits a charged carrier, responding to ultimate low-frequency oscillations in the scattered correlations. The fit function of long-time oscillation in correlation is presented by an alternating cosine function with a phase, which is related to its possible dynamic elelctrophoretic mobility.
Investigation of the friction coefficient evolution and lubricant breakdown behaviour of AA7075 aluminium alloy forming processes at elevated temperatures
Authors: Yang Xiao , Zhang Qunli , Zheng Yang , Liu Xiaochuan , Politis Denis , Fakir Omer El , Wang Liliang
Published: February 2021

The lubricant behaviour at elevated temperatures was investigated by conducting pin-on-disc tests between P20 tool steel and AA7075 aluminium alloy. The effects of temperature, initial lubricant volume, contact pressure and sliding speed on the lubricant behaviour (i.e. evolutions of the coefficient of friction (COF) and the breakdown phenomenon) were experimentally studied. The evolutions of COF at elevated temperatures consisted of three distinct stages with different friction mechanisms. The first stage (stage I) occurred with low friction when the boundary lubrication was present. The second stage (stage II) was the transition process in which the COF rapidly increased as the lubricant film thickness decreased to a critical value. In the final plateau stage (stage III), lubricant breakdown occurred and intimate contact at the interface led to high friction values. At the low friction stage (stage I), the value of COF increased with increasing temperature. The increase in temperature, contact pressure and sliding speed as well as the decrease in initial lubricant volume accelerated the lubricant breakdown.
Active damping of rotating platforms using integral force feedback
Authors: Dehaeze Thomas , Collette Christophe
Published: February 2021

This paper investigates the use of Integral Force Feedback (IFF) for the active damping of rotating mechanical systems. Guaranteed stability, typical benefit of IFF, is lost as soon as the system is rotating due to gyroscopic effects. To overcome this issue, two modifications of the classical IFF control scheme are proposed. The first consists of slightly modifying the control law while the second consists of adding springs in parallel with the force sensors. Conditions for stability and optimal parameters are derived. The results reveal that, despite their different implementations, both modified IFF control scheme have almost identical damping authority on the suspension modes.
Efficient training of energy-based models via spin-glass control
Authors: Pozas-Kerstjens Alejandro , Muñoz-Gil Gorka , Piñol Eloy , García-March Miguel Ángel , Acín Antonio , Lewenstein Maciej , Grzybowski Przemysław R
Published: February 2021

We introduce a new family of energy-based probabilistic graphical models for efficient unsupervised learning. Its definition is motivated by the control of the spin-glass properties of the Ising model described by the weights of Boltzmann machines. We use it to learn the Bars and Stripes dataset of various sizes and the MNIST dataset, and show how they quickly achieve the performance offered by standard methods for unsupervised learning. Our results indicate that the standard initialization of Boltzmann machines with random weights equivalent to spin-glass models is an unnecessary bottleneck in the process of training. Furthermore, this new family allows for very easy access to low-energy configurations, which points to new, efficient training algorithms. The simplest variant of such algorithms approximates the negative phase of the log-likelihood gradient with no Markov chain Monte Carlo sampling costs at all, and with an accuracy sufficient to achieve good learning and generalization.
Study of mechanical, electrical and EMI shielding properties of polymer-based nanocomposites incorporating polyaniline coated graphene nanoparticles
Authors: Zubair Khadija , Ashraf Ahmad , Gulzar Haseeb , Shakir M Fayzan , Nawab Yasir , Rehan Z A , Rashid Iqra Abdul
Published: February 2021

The Electromagnetic Interference (EMI) shielding characteristics of PVC based nanocomposites were studied when reinforced with newly developed Thermally Reduced Graphene Oxide (TRGO) coated with Polyaniline (PANI) nanoparticles. Various techniques were utilized to characterize prepared nanocomposite films like Scanning Electron Microscopy (SEM), direct current (DC) conductivity measurement, impedance analyses, and EMI shielding. EMI shielding was measured in three different regions of the electromagnetic spectrum like the Microwave region (0.1 GHz to 20 GHz), Near InfraRed (NIR), and Ultraviolet region (UV). The coating of PANI over TRGO provides compatibility of nanoparticles with a polymer matrix that leads to enhanced dispersion. EMI shielding was found to be 104 dB for 40 wt% filler content, because of the formation of a mature and dense interconnected network structure of filler. UV and NIR transmittance was also studied and less than 0.5% transmission in the whole UV (200 nm 400 nm) and NIR (700 nm 2500 nm) region was observed.
Transporting Subgroup Analyses of Randomized Controlled Trials for Planning Implementation of New Interventions
Authors: Mehrotra Megha L , Westreich Daniel , Glymour M Maria , Geng Elvin , Glidden David V
Published: February 2021

Subgroup analyses of randomized controlled trials guide resource allocation and implementation of new interventions by identifying groups of individuals who are likely to benefit most from the intervention. Unfortunately, trial populations are rarely representative of the target populations of public health or clinical interest. Unless the relevant differences between trial and target populations are accounted for, subgroup results from trials might not reflect which groups in the target population will benefit most from the intervention. Transportability provides a rigorous framework for applying results derived in potentially highly selected study populations to external target populations. The method requires that researchers measure and adjust for all variables that 1) modify the effect of interest and 2) differ between the target and trial populations. To date, applications of transportability have focused on the external validity of overall study results and understanding within-trial heterogeneity; however, this approach has not yet been used for subgroup analyses of trials. Through an example from the Iniciativa Profilaxis Pre-Exposición (iPrEx) study (multiple countries, 2007–2010) of preexposure prophylaxis for human immunodeficiency virus, we illustrate how transporting subgroup analyses can produce target-specific subgroup effect estimates and numbers needed to treat. This approach could lead to more tailored and accurate guidance for resource allocation and cost-effectiveness analyses.
Does the Fast Alcohol Screening Test Accurately Distinguish Between Harmful and Severely Dependent Tiers of Alcohol Misuse?
Authors: John Bev , Newstead Simon , Heirene Robert , Hodgson Ray , Roderique-Davies Gareth
Published: February 2021

Aims

Primary aim: to determine the efficacy of FAST (the Fast Alcohol Screening Test) for detecting harmful and dependent levels of alcohol use. Secondary aim: to compare the performance of the FAST to two short forms of the Alcohol Use Disorder Identification Test (AUDIT): the AUDIT-C and AUDIT-3.

Methods

Data from 3336 individuals in South Wales, compiled from full AUDIT datasets, were examined. AUROC analysis, alongside measures of sensitivity and specificity of the FAST, AUDIT-C and AUDIT-3 were utilized for the identification of harmful and dependent alcohol use.

Results

The FAST demonstrated efficacy in the identification of harmful and dependent levels of alcohol use, with superior performance to both the AUDIT-C and AUDIT-3.

Conclusion

The present paper demonstrates the potential of the FAST as a cost- and time-effective method for appropriate screening and signposting in the stepped care model utilized by many health care and treatment services. Further studies are needed to ensure validity, both within the general population and for specific services and populations.
Comparative phylogeography of two Northern Rocky Mountain endemics: the widespread Anguispira kochi occidentalis and the narrow-range Anguispira nimapuna (Gastropoda: Discidae)
Authors: Rankin Andrew M , Anderson Frank E , Clutts Stephanie A , Espíndola Anahí , Carstens Bryan C , Lucid Michael , Sullivan Jack
Published: February 2021

The Northern Rocky Mountain ecosystem supports rich biological diversity with many endemic and rare species. Extant endemics display two biogeographic patterns: widespread species with fragmented populations, and narrow-range endemics. These distributions are shown by the congeneric snails Anguispira kochi occidentalis and Anguispira nimapuna. These two taxa are disjunct from the remaining species of the genus, which achieves its greatest diversity in eastern North America. Given the disjunct nature of A. k. occidentalis and A. nimapuna, we here present a mtDNA phylogeny of the genus that includes both eastern and western species to assess the phylogenetic position of A. k. occidentalis and A. nimapuna. We then reconstruct the demographic history of A. k. occidentalis and A. nimapuna by analysing current patterns of genetic variation and interpreting the results considering the historical biogeography of the region. Both A. k. occidentalis and A. nimapuna represent unique taxa that are genetically and geographically distinct from their congeners. The current distribution and genetic structure of A. k. occidentalis has been shaped by both historical isolation in refugia and more recent northward shifts, whereas A. nimapuna is represented by two populations with shallow divergence in an area of long-term habitat stability.
Long-term survival after self-expanding metallic stent or stoma decompression as bridge to surgery in acute malignant large bowel obstruction
Authors: Axmarker T , Leffler M , Lepsenyi M , Thorlacius H , Syk I
Published: February 2021

Aim

Self-expanding metallic stents (SEMS) as bridge to surgery have been questioned due to the fear of perforation and tumour spread. This study aimed to compare SEMS and stoma as bridge to surgery in acute malignant large bowel obstruction in the Swedish population.

Method

Medical records of patients identified via the Swedish Colorectal Cancer Register 2007–2009 were collected and scrutinized. The inclusion criterion was decompression intended as bridge to surgery due to acute malignant large bowel obstruction. Patients who underwent decompression for other causes or had bowel perforation were excluded. Primary endpoints were 5-year overall survival and 3-year disease-free survival. Secondary endpoints were 30-day morbidity and mortality rates.

Results

A total of 196 patients fulfilled the inclusion criterion (SEMS, 71, and stoma, 125 patients). There was no significant difference in sex, age, ASA score, TNM stage and adjuvant chemotherapy between the SEMS and stoma groups. No patient was treated with biological agents. Five-year overall survival was comparable in SEMS, 56 per cent (40 patients), and stoma groups, 48 per cent (60 patients), P = 0.260. Likewise, 3-year disease-free survival did not differ statistically significant, SEMS 73 per cent (43 of 59 patients), stoma 65 per cent (62 of 95 patients), P = 0.32. In the SEMS group, 1.4 per cent (one patient) did not fulfil resection surgery compared to 8.8 per cent (11 patients) in the stoma group (P = 0.040). Postoperative complication and 30-day postoperative mortality rates did not differ, whereas the duration of hospital stay and proportion of permanent stoma were lower in the SEMS group.

Conclusion

This nationwide registry-based study showed that long-term survival in patients with either SEMS or stoma as bridge to surgery in acute malignant large bowel obstruction were comparable. SEMS were associated with a lower rate of permanent stoma, higher rate of resection surgery and shorter duration of hospital stay.
RLIP depletion induces apoptosis associated with inhibition of JAK2/STAT3 signaling in melanoma cells
Authors: Singhal Sharad S , Mohanty Atish , Kulkarni Prakash , Horne David , Awasthi Sanjay , Salgia Ravi
Published: February 2021

The incidence of malignant melanoma, a neoplasm of melanocytic cells, is increasing rapidly. The lymph nodes are often the first site of metastasis and can herald systemic dissemination, which is almost uniformly fatal. RLIP, a multi-specific ATP-dependent transporter that is over-expressed in several types of cancers, plays a central role in cancer cell resistance to radiation and chemotherapy. RLIP appears to be necessary for cancer cell survival because both in vitro cell culture and in vivo animal tumor studies show that the depletion or inhibition of RLIP causes selective toxicity to malignant cells. RLIP depletion/inhibition triggers apoptosis in cancer cells by inducing the accumulation of endogenously formed glutathione-conjugates. In our in vivo studies, we administered RLIP antibodies or antisense oligonucleotides to mice bearing subcutaneous xenografts of SKMEL2 and SKMEL5 melanoma cells and demonstrated that both treatments caused significant xenograft regression with no apparent toxic effects. Anti-RLIP antibodies and antisense, which respectively inhibit RLIP-mediated transport and deplete RLIP expression, showed similar tumor regressing activities, indicating that the inhibition of RLIP transport activity at the cell surface is sufficient to achieve anti-tumor activity. Furthermore, RLIP antisense treatment reduced levels of RLIP, pSTAT3, pJAK2, pSrc, Mcl-1 and Bcl2, as well as CDK4 and cyclin B1, and increased levels of Bax and phospho 5’ AMP-activated protein kinase (pAMPK). These studies indicate that RLIP serves as a key effector in the survival of melanoma cells and is a valid target for cancer therapy. Overall, compounds that inhibit, deplete or downregulate RLIP will function as wide-spectrum agents to treat melanoma, independent of common signaling pathway mutations.
Antibiotic Use and Presumptive Pathogens in the Veterans Affairs Healthcare System
Authors: Tedijanto Christine , Nevers McKenna , Samore Matthew H , Lipsitch Marc
Published: February 2021

Background

Empirical antibiotic use is common in the hospital. Here, we characterize patterns of antibiotic use, infectious diagnoses, and microbiological laboratory results among hospitalized patients and aim to quantify the proportion of antibiotic use that is potentially attributable to specific bacterial pathogens.

Methods

We conducted an observational study using electronic health records from acute care facilities in the US Veterans Affairs Healthcare System. From October 2017 to September 2018, 482 381 hospitalizations for 332 657 unique patients that met all criteria were included. At least 1 antibiotic was administered at 202 037 (41.9%) of included hospital stays. We measured frequency of antibiotic use, microbiological specimen collection, and bacterial isolation by diagnosis category and antibiotic group. A tiered system based on specimen collection sites and diagnoses was used to attribute antibiotic use to presumptive causative organisms.

Results

Specimens were collected at 130 012 (64.4%) hospitalizations with any antibiotic use, and at least 1 bacterial organism was isolated at 35.1% of these stays. Frequency of bacterial isolation varied widely by diagnosis category and antibiotic group. Under increasingly lenient criteria, 10.2%–31.4% of 974 733 antibiotic days of therapy could be linked to a potential bacterial pathogen.

Conclusions

Overall, the vast majority of antibiotic use could be linked to either an infectious diagnosis or microbiological specimen. Nearly one-half of antibiotic use occurred when there was a specimen collected but no bacterial organism identified, underscoring the need for rapid and improved diagnostics to optimize antibiotic use.
The Effects of Using a Clinical Prediction Rule to Prioritize Diagnostic Testing on Transmission and Hospital Burden: A Modeling Example of Early Severe Acute Respiratory Syndrome Coronavirus 2
Authors: Reimer Jody R , Ahmed Sharia M , Brintz Ben J , Shah Rashmee U , Keegan Lindsay T , Ferrari Matthew J , Leung Daniel T
Published: February 2021

Background

Prompt identification of infections is critical for slowing the spread of infectious diseases. However, diagnostic testing shortages are common in emerging diseases, low resource settings, and during outbreaks. This forces difficult decisions regarding who receives a test, often without knowing the implications of those decisions on population-level transmission dynamics. Clinical prediction rules (CPRs) are commonly used tools to guide clinical decisions.

Methods

Using early severe acute respiratory syndrome coronavirus disease 2 (SARS-CoV-2) as an example, we used data from electronic health records to develop a parsimonious 5-variable CPR to identify those who are most likely to test positive. To consider the implications of gains in daily case detection at the population level, we incorporated testing using the CPR into a compartmentalized model of SARS-CoV-2.

Results

We found that applying this CPR (area under the curve, 0.69; 95% confidence interval, .68–.70) to prioritize testing increased the proportion of those testing positive in settings of limited testing capacity. We found that prioritized testing led to a delayed and lowered infection peak (ie, “flattens the curve”), with the greatest impact at lower values of the effective reproductive number (such as with concurrent community mitigation efforts), and when higher proportions of infectious persons seek testing. In addition, prioritized testing resulted in reductions in overall infections as well as hospital and intensive care unit burden.

Conclusion

We highlight the population-level benefits of evidence-based allocation of limited diagnostic capacity.

Summary

When the demand for diagnostic tests exceeds capacity, the use of a clinical prediction rule to prioritize diagnostic testing can have meaningful impact on population-level outcomes, including delaying and lowering the infection peak, and reducing healthcare burden.
Full, Partial, and Modified Permutations of the Mayo Score: Characterizing Clinical and Patient-Reported Outcomes in Ulcerative Colitis Patients
Authors: Naegeli April N , Hunter Theresa , Dong Yan , Hoskin Ben , Middleton-Dalby Chloe , Hetherington James , Stefani-Hunyady Diana , Canavan James B
Published: February 2021

Background

Understanding ulcerative colitis disease activity assessed via the full, modified, or partial Mayo Score may help clinicians apply results from clinical trials to practice and facilitate interpretation of recent and older studies.

Methods

Mayo Score variables were assessed in a cross-sectional study of 2608 ulcerative colitis patients.

Results

Permutations of Mayo Scores were highly correlated, and models predicting the omitted variable from each permutation demonstrated significant agreement between predicted and observed values.

Conclusions

Partial/modified Mayo Scores may be used to predict endoscopic and Physician’s Global Assessment scores, and serve as proxies for the full Mayo Score in clinical practice/trials.
Going from bad to worse: from Internet voting to blockchain voting
Authors: Park Sunoo , Specter Michael , Narula Neha , Rivest Ronald L
Published: February 2021

Voters are understandably concerned about election security. News reports of possible election interference by foreign powers, of unauthorized voting, of voter disenfranchisement, and of technological failures call into question the integrity of elections worldwide. This article examines the suggestions that “voting over the Internet” or “voting on the blockchain” would increase election security, and finds such claims to be wanting and misleading. While current election systems are far from perfect, Internet- and blockchain-based voting would greatly increase the risk of undetectable, nation-scale election failures. Online voting may seem appealing: voting from a computer or smartphone may seem convenient and accessible. However, studies have been inconclusive, showing that online voting may have little to no effect on turnout in practice, and it may even increase disenfranchisement. More importantly, given the current state of computer security, any turnout increase derived from Internet- or blockchain-based voting would come at the cost of losing meaningful assurance that votes have been counted as they were cast, and not undetectably altered or discarded. This state of affairs will continue as long as standard tactics such as malware, zero day, and denial-of-service attacks continue to be effective. This article analyzes and systematizes prior research on the security risks of online and electronic voting, and shows that not only do these risks persist in blockchain-based voting systems, but blockchains may introduce ‘additional’ problems for voting systems. Finally, we suggest questions for critically assessing security risks of new voting system proposals.