bluuebunny/crossref_metadata_2025 huggingface dataset:
Space–time histories approach to fast stochastic simulation of bimolecular reactions
Authors: Prüstel Thorsten , Meier-Schellersheim Martin
Published: April 2021

Computational models of reaction–diffusion systems involving low copy numbers or strongly heterogeneous molecular spatial distributions, such as those frequently found in cellular signaling pathways, require approaches that account for the stochastic dynamics of individual particles, as opposed to approaches representing them through their average concentrations. Efforts to remedy the high computational cost associated with particle-based stochastic approaches by taking advantage of Green’s functions are hampered by the need to draw random numbers from complicated, and therefore costly, non-standard probability distributions to update particle positions. Here, we introduce an approach that permits the reconstruction of entire molecular trajectories, including bimolecular encounters, in retrospect, after a simulated time step, while avoiding inefficient draws from non-standard distributions. This means that highly accurate stochastic simulations can be performed for system sizes that would be prohibitively costly to simulate with conventional Green’s function based methods. The algorithm applies equally well to one, two, and three dimensional systems and can be readily extended to include deterministic forces specified by an interaction potential, such as the Coulomb potential.
Multi-body effects in a coarse-grained protein force field
Authors: Wang Jiang , Charron Nicholas , Husic Brooke , Olsson Simon , Noé Frank , Clementi Cecilia
Published: April 2021

The use of coarse-grained (CG) models is a popular approach to study complex biomolecular systems. By reducing the number of degrees of freedom, a CG model can explore long time- and length-scales inaccessible to computational models at higher resolution. If a CG model is designed by formally integrating out some of the system’s degrees of freedom, one expects multi-body interactions to emerge in the effective CG model’s energy function. In practice, it has been shown that the inclusion of multi-body terms indeed improves the accuracy of a CG model. However, no general approach has been proposed to systematically construct a CG effective energy that includes arbitrary orders of multi-body terms. In this work, we propose a neural network based approach to address this point and construct a CG model as a multi-body expansion. By applying this approach to a small protein, we evaluate the relative importance of the different multi-body terms in the definition of an accurate model. We observe a slow convergence in the multi-body expansion, where up to five-body interactions are needed to reproduce the free energy of an atomistic model.
Speeding up Hartree–Fock and Kohn–Sham calculations with first-order corrections
Authors: Csóka József , Kállay Mihály
Published: April 2021

Several approaches are presented to improve the efficiency of Hartree–Fock and Kohn–Sham self-consistent field (SCF) calculations relying on a simple first-order energy correction reminiscent of the scheme used in dual-basis SCF methods. The basic idea is to perform an initial SCF calculation computing approximate Fock-matrices and, in the final iteration step, to use a more complete Fock-matrix builder together with the energy correction to diminish the error. The approximation is tested for conventional and local density fitting (DF) SCF approaches combining various auxiliary basis sets, fitting metrics, and Fock-matrix construction algorithms in the initial and final iterations as well as for seminumerical SCF methods combining integration grids of different qualities. We also report the implementation of the occupied orbital resolution of identity exchange construction algorithm with local DF approximations. Benchmark calculations are presented for total energies, reaction energies, and molecular geometries. Our results show that speedups of up to 80% can be expected utilizing the new approaches without significant loss of accuracy.
For an ab initio calculation of the magnetic excitations: RelaxSE!
Authors: Rebolini Elisa , Lepetit Marie-Bernadette
Published: April 2021

In this paper, we present a novel efficient and parallel implementation, RelaxSE, for the calculation of the low-lying excited states and energies of strongly correlated systems. RelaxSE is based on the fully uncontracted multi-reference method of Selected Active Space + Single excitations. This method has been specifically designed to be able to tackle systems with numerous open shells per atoms. It is, however, computationally challenging due to the rapid scaling of the number of determinants and their non-trivial ordering induced by the selection process. We propose a combined determinant-driven and integral-driven approach designed for hybrid OpenMP/MPI parallelization. The performances of RelaxSE are evaluated on a controlled test set and show linear scaling with respect to the number of determinants and a small overhead due to the parallelization. Systems with up to 1 × 109 determinants are successfully computed.
Structural, electronic, and charge transfer features for two kinds of MoS2/Cs2PbI4 interfaces with optoelectronic applicability: Insights from first-principles
Authors: Zhao Yu-Qing , Liu Zhao-Sheng , Nie Guo-Zheng , Zhu Zhong-Hua , Chai Yi-Feng , Wang Jun-Nian , Cai Meng-Qiu , Jiang Shaolong
Published: April 2021

Low-dimensional transitional metal sulfide and halide perovskite heterostructures have attracted considerable attention due to their wide applicability in optoelectronics. We present detailed research that combines two-dimensional MoS2 and Cs2PbI4 into heterostructures and investigate the electronic structure, charge carrier transfer, and optical properties of two kinds of heterostructures (1T-MoS2/Cs2PbI4 and 2H-MoS2/Cs2PbI4) based on density functional theory. It is predicted that both interfacial contacts for 1T-MoS2/Cs2PbI4 exhibit p-type Schottky contacts and the Schottky barrier heights of interfacial contacts can be largely tuned based on interfacial engineering. The 2H-MoS2/Cs2PbI4 heterostructure demonstrates type II band alignment, which can effectively enhance photogenerated carrier separation and optical absorption coefficients. The tunable Schottky barrier heights in 1T-MoS2/Cs2PbI4 and the type II band alignment in the 2H-MoS2/Cs2PbI4 heterostructure would provide the potential application in future designs of field effect transistor and photovoltaic applications.
Mathematical model and analysis method for flowfield separation and transition
Authors: Yue Peng , Xiao Jingping , Xu Ke , Li Ming , Jiang Feng , Lu Yiyu , Peng Dewei
Published: April 2021

Transition and separation are difficult but important problems in the field of fluid mechanics. Hitherto, separation and transition problems have not been described accurately in mathematical terms, leading to design errors and prediction problems in fluid machine engineering. The nonlinear uncertainty involved in separation and transition makes it difficult to accurately analyze these phenomena using experimental methods. Thus, new ideas and methods are required for the mathematical prediction of fluid separation and transition. In this article, after an axiomatic treatment of fluid mechanics, the concept of an excited state is derived by generating a fluctuation velocity, and it is revealed that fluid separation and transition are special forms of this excited state. This allows us to clarify the state conditions of fluid separation and transition. Mathematical analysis of the Navier–Stokes equations leads to a general excited state theorem suitable for flowfields. Finally, the conditions of separation and transition are derived, and the corresponding general laws are established. The results presented in this article provide a foundation for future research on the mechanism of turbulence and the solution of engineering problems.
Defects induced persistent photoconductivity in monolayer MoS2
Authors: Chandan  , Sarkar Suman , Angadi Basavaraj
Published: April 2021

Understanding the relaxation mechanisms of photoexcited charge carriers in two-dimensional materials is indispensable from the fundamental point of view and for future optoelectronic applications. Through the photoconductivity and electronic transport experiments, we probe the mechanisms behind the persistent photoconductivity (PPC) in monolayer molybdenum disulfide (MoS2). The temperature (T) and power-dependent photoresponse studies reveal that the relaxation of excited charge carriers is strongly affected by the random fluctuations of local potentials. The relaxation time (τ) increases from τ ≃ 12 s at T = 16.5 K to τ ≃ 1235 s at T = 297 K, indicating PPC is a high T phenomenon in monolayer MoS2. The transport measurements demonstrate that the defect states with the density ≃4.43 × 1014 eV−1 cm–2 in a low gate voltage regime, originating from the sulfur vacancies, are responsible for these fluctuations. With a rise in temperature, the defect states undergo a transition from localization to extended states at T ≥ 100 K and thereby form the percolation network, which profoundly influences the relaxation mechanism. Our meticulous experiments and quantitative analysis provide newer insight into the origin of PPC in monolayer MoS2.
Explicit wall models for large eddy simulation
Authors: Cai Shang-Gui , Sagaut Pierre
Published: April 2021

Algebraic explicit wall models covering the entire inner region of the turbulent boundary layer are proposed to reduce the computational effort for large eddy simulation of wall-bounded turbulent flows. The proposed formulas are given in closed forms with either logarithmic- or power-function-based laws of the wall, allowing straightforward evaluation of the friction velocity on near wall grids independent of their locations in the turbulent boundary layer. The performance of the proposed models is demonstrated by the wall modeled large eddy simulation of a turbulent plane channel flow.
Donor–acceptor complex formation in tetra-n-butylammonium chloride: n-decanoic acid deep eutectic solvent
Authors: Dhingra Divya , Khokhar Vaishali , Juneja Shreya , Pandey Siddharth
Published: April 2021

Complex formation between pyrene (Py) and N,N-dimethylaniline (DMA) is presented in a deep eutectic solvent constituting of tetra-n-butylammonium chloride (TBAC) and n-decanoic acid (DA) in a 1:2 mol ratio, respectively, named TBAC:DA. The addition of DMA to a Py solution of TBAC:DA results in the formation of a fluorescent Py-DMA charge-transfer complex, which is manifested via a broad structureless bathochromically shifted band centered at 550(±2) nm. The solvatochromic nature of the Py-DMA fluorescent complex indicates the solvent polarity of TBAC:DA to be higher than that of methanol. The absence of a negative pre-exponential factor in the intensity decay at 550 nm combined with the excitation scans implies the presence of weak interaction between Py and DMA in the ground-state, leading to the rapid formation of a Py-DMA complex possibly at a sub-nanosecond time scale. The Stern–Volmer quenching constant (KSV) varies from 53(±2) to 96(±1) M−1, and the bimolecular quenching rate constant (kq) varies from 3.0(±0.4) × 108 to 8.8(±1.3) × 108 M−1 s−1 by increasing the temperature (T) from 283.15 to 313.15 K, implying efficient deactivation of electron-acceptor Py in the excited-state induced effectively by the electron-donor DMA within TBAC:DA. ln kq varies linearly with 1/T with an activation energy (Ea) of 26.4(±0.4) kJ mol−1. The linear behavior between kq and 1/η suggests conformity to the Stokes–Einstein relationship within TBAC:DA. The Py-DMA complex formation efficiency increases with an increase in T and reaches maxima at 298.15 K before decreasing with a further increase in T. The initial reduction in η favors Py-DMA complex formation; this effect is overcome by preferential thermal deactivation of the Py-DMA fluorescent complex as compared to that of pyrene.
Spontaneous ignition of soils: a multi-step reaction scheme to simulate self-heating ignition of smouldering peat fires
Authors: Yuan Han , Restuccia Francesco , Rein Guillermo
Published: April 2021

As organic porous soil, peat is prone to self-heating ignition, a type of spontaneous initiation of fire that can take place at ambient temperatures without an external source. Despite the urgency to tackle peat fires, the understanding of the self-heating ignition of peat is insufficient. In this study, a computational model that integrates the mechanisms of heat transfer, mass transfer and chemistry is incorporated with a three-step reaction scheme that includes drying, biological reaction and oxidative oxidation to simulate the self-heating ignition of smouldering peat. The model is first validated against 13 laboratory-scale experiments from literature. For critical ignition temperature (Tig), the model gives accurate predictions for all experiments with a maximum error of 5°C. The validated model is then upscaled to predict Tig for field-size peat soil layers and compared with the predictions using a one-step scheme. The three-step scheme is shown to give more reliable predictions of Tig than the one-step scheme. According to the simulation results, for a 1.5-m-deep peat layer, self-heating ignition can occur at an average ambient temperature above 40°C. This is the first time that a multi-step scheme is used to simulate the self-heating ignition of peat, aiming to help in the prevention and mitigation of these wildfires.
A Sos proteomimetic as a pan-Ras inhibitor
Authors: Hong Seong Ho , Yoo Daniel Y. , Conway Louis , Richards-Corke Khyle C. , Parker Christopher G. , Arora Paramjit S.
Published: April 2021

Significance

Oncogenic Ras isoforms are the subject of intense study due to the difficulty in targeting these biomedically important yet “undruggable” proteins. Recent success in covalent targeting of a Ras mutant illustrates avenues for ligand design; however, many mutant Ras forms do not feature appropriately-placed nucleophiles, suggesting that strategies for noncovalent engagement of Ras are required. We report the design of a conformationally-defined proteomimetic that reproduces a key binding surface of Sos, a well-characterized effector of Ras. The proteomimetic binds wild-type and various mutant forms of Ras and modulates downstream signaling. Significantly, the compound shows enhanced internalization and selective toxicity toward cancer cells that up-regulate macropinocytosis. We anticipate these studies will foster new therapeutic modalities to engage mutant Ras.
The grain refinement of aluminium by a new as-cast Al–Ti–TiCN composite
Authors: Yang Wen , Tang Zhenghua , Yuan Mingwan , Sun Weijian , Xiao Sufen
Published: April 2021

A new type of composite refiner Ti/TiCN is prepared by loading submicron-TiCN particles onto Ti micron-particles and added to industrial pure aluminium. Refining mechanism has been characterised in detail by optical microscopy, scanning electron microscopy and transmission electron microscopy coupled with energy disperse X-ray spectra. These experimental results show that Ti/TiCN inoculation is more effective in refining pure aluminium than Ti and TiCN added separately. The relationship between grain size and growth restriction factors of aluminium matrix containing Ti/TiCN refiner is d = 70.2 + 1190.8/ Q. According to the free growth theory, aluminium matrix with Ti/TiCN inoculation has the largest solidification driving force to promote grain nucleation under the same growth restriction factors ( Q = 0.5,1, 5, 12, 20 K) compared to Ti and TiCN refiners.
Rac1-PAK1 regulation of Rab11 cycling promotes junction destabilization
Authors: Erasmus Jennifer C. , Smolarczyk Kasia , Brezovjakova Helena , Mohd-Naim Noor F. , Lozano Encarnación , Matter Karl , Braga Vania M.M.
Published: April 2021

Rac1 GTPase is hyperactivated in tumors and contributes to malignancy. Rac1 disruption of junctions requires its effector PAK1, but the precise mechanisms are unknown. Here, we show that E-cadherin is internalized via micropinocytosis in a PAK1–dependent manner without catenin dissociation and degradation. In addition to internalization, PAK1 regulates E-cadherin transport by fine-tuning Rab small GTPase function. PAK1 phosphorylates a core Rab regulator, RabGDIβ, but not RabGDIα. Phosphorylated RabGDIβ preferentially associates with Rab5 and Rab11, which is predicted to promote Rab retrieval from membranes. Consistent with this hypothesis, Rab11 is activated by Rac1, and inhibition of Rab11 function partially rescues E-cadherin destabilization. Thus, Rac1 activation reduces surface cadherin levels as a net result of higher bulk flow of membrane uptake that counteracts Rab11-dependent E-cadherin delivery to junctions (recycling and/or exocytosis). This unique small GTPase crosstalk has an impact on Rac1 and PAK1 regulation of membrane remodeling during epithelial dedifferentiation, adhesion, and motility.
A review of geometric and structural design for reliable flexible electronics
Authors: Yoo Jae-Young , Yang Jae-Soon , Chung Myung-Kun , Kim Sung-Ho , Yoon Jun-Bo
Published: April 2021

Recently, flexible electronics have attracted significant attention as they can be integrated on diverse platforms from curved to flexible surfaces. As flexible electronics are used on a curved surface of wearable or manufacturing devices for health and system monitoring, the working environment of such applications forces electronics to be exposed to diverse stimuli such as deformation, temperature, humidity, and gas, resulting in performance changes. Therefore, rather than research on improving the specific performance of electronics, research on maintaining a stable performance in various environmental stimuli has been receiving tremendous interest. Reflecting the latest research trends, this paper introduces efforts in structural designs heading for both improving and maintaining the performance of flexible electronics in diverse environmental stimuli. Firstly, we will sequentially explain the geometric and structural designs introduced for achieving (a) reliable electronics insensitive to undesired mechanical stimuli, (b) reliable electronics in harsh environments, and (c) flexible electrodes. Also, (d) diverse applications of reliable and flexible electronics are introduced. Finally, a perspective on reliable and flexible electronic devices has been presented for suggesting next-generation research.
Interaction between negative corona discharge and droplet emission from liquid Taylor cone
Authors: Nakagawa Yusuke , Nagao Keisuke , Tochikubo Fumiyoshi
Published: April 2021

We investigated the behavior of droplets, the Taylor cone tip, and discharge current characteristics in electrospraying with negative corona discharge, and analyzed the interaction among them in the time scale of several micro seconds. Negative corona discharges using 1 wt% sodium dodecyl sulfate solution or ethylene glycol as liquid cathode were investigated, and the discharge current pulse had a distinctive structure with serial pulse trains. The pulse train structure indicated that the discharges from the Taylor cone are in the form of Trichel pulses with a dynamic cathode. We found that the electric field, liquid conductivity, and liquid viscosity had no significant effect on the discharge current characteristics, with the exception of the current peak value, whereas a higher electric field or higher liquid viscosity led to extended pulse train intervals and durations. These effects can be attributed to the change in time scale of the cone tip curvature variation. The above results indicate that the curvature radius of the cone tip dominates the discharges from the Taylor cone. The emission and transfer of droplets between electrodes were observed using back-lit images and Mie-scattered light images taken by a high-speed camera. The droplet emission was synchronized with the leading current in the Trichel pulses. The terminal velocity of the droplets transferring discharge gap was proportional to the revised electric field. The experimental results indicate that the droplet emission mechanism from the Taylor cone with discharges is supposed to differ from that without discharges explained by the Rayleigh limit. The reasonable explanation for the droplet emission mechanism is that the droplets are torn off the liquid cone tip by the strong electric field associated with discharges.
Theoretical insights into the mechanism of oxygen evolution reaction (OER) on pristine BiVO4 (001) and BiVO4 (110) surfaces in acidic medium both in the gas and solution (water) phases
Authors: Bhatt Mahesh Datt , Lee Jin Yong
Published: April 2021

Monoclinic scheelite bismuth vanadate is an efficient photocatalyst for water splitting. In this paper, we perform DFT + U calculations to investigate the structural, electronic, and optical properties, water adsorption and the oxygen evolution reaction processes on BiVO4 (001) and BiVO4 (110) surfaces in acidic medium both in the gas and solution (water) phases. The structural, electronic, optical, and water adsorption properties reveal that BiVO4 (001) surface is energetically more stable than BiVO4 (110) surface in vacuum. On other hand, the water oxidation mechanisms reveal that BiVO4 (110) surface in water and in strained form in vacuum is energetically more stable than BiVO4 (001) surface in water and in strained form in vacuum both U = 0 and 2.1 V. The free energy of adsorption for all systems at U = 2.1 V reduce about 2 times than that at U = 0 V. Such analyzes provide important insights into the role of different facets on BiVO4 surface for photocatalytic reactions.
Pancreas segmentation with probabilistic map guided bi-directional recurrent UNet
Authors: Li Jun , Lin Xiaozhu , Che Hui , Li Hao , Qian Xiaohua
Published: April 2021

Pancreas segmentation in medical imaging is of great significance for clinical pancreas diagnostics and treatment. However, the large population variations in the pancreas shape and volume cause enormous segmentation difficulties, even for state-of-the-art algorithms utilizing fully convolutional neural networks (FCNs). Specifically, pancreas segmentation suffers from the loss of statement temporal information in 2D methods, and the high computational cost of 3D methods. To alleviate these problems, we propose a probabilistic-map-guided bi-directional recurrent UNet (PBR-UNet) architecture, which fuses intra-slice information and inter-slice probabilistic maps into a local 3D hybrid regularization scheme, which is followed by a bi-directional recurrent optimization scheme. The PBR-UNet method consists of an initial estimation module for efficiently extracting pixel-level probabilistic maps and a primary segmentation module for propagating hybrid information through a 2.5D UNet architecture. Specifically, local 3D information is inferred by combining an input image with the probabilistic maps of the adjacent slices into multi-channel hybrid data, and then hierarchically aggregating the hybrid information of the entire segmentation network. Besides, a bi-directional recurrent optimization mechanism is developed to update the hybrid information in both the forward and the backward directions. This allows the proposed network to make full and optimal use of the local context information. Quantitative and qualitative evaluation was performed on the NIH Pancreas-CT and MSD pancreas dataset, and our proposed PBR-UNet method achieved similar segmentation results with less computational cost compared to other state-of-the-art methods.
Coherent radiation of active Josephson traveling-wave antennas
Authors: Galin M А , Shereshevsky I A , Vdovicheva N K , Kurin V V
Published: April 2021

The dynamics of large superwavelength open systems which are free-standing multi-wire lines with a large number of Josephson junctions, DC bias batteries and other lumped elements is analyzed using direct numerical simulation. Such systems represent the simplest version of the active Josephson antennas proposed in our earlier studies and show promise as terahertz and subterahertz radiation sources. We have studied dependences of the radiation characteristics on the antenna geometry, number of junctions, DC bias current and the lumped elements position and parameters. Detailed simulation results reveal a multitude of phase transitions between the dynamical states, which differ in the number of Josephson junctions synchronized by the excited waves of current and, hence, in the radiation power emitted into open space also as in radiation patterns. It is shown that, in the absence of noise, the Josephson antennas can emit completely coherent radiation.
Hubbard models and state preparation in an optical Lieb lattice
Authors: Flannigan S , Madail L , Dias R G , Daley A J
Published: April 2021

Inspired by the growing interest in probing many-body phases in novel two-dimensional lattice geometries we investigate the properties of cold atoms as they could be observed in an optical Lieb lattice. We begin by computing Wannier functions localised at individual sites for a realistic experimental setup, and determining coefficients for a Hubbard-like model. Based on this, we show how experiments could probe the robustness of edge states in a Lieb lattice with diagonal boundary conditions to the effects of interactions and realise strongly correlated many-body phases in this geometry. We then generalise this to interacting particles in a half-filled 1D Lieb ladder, where excitations are dominated by flat band states. We show that for strong attractive interactions, pair correlations are enhanced even when there is strong mixing with the Dirac cone. These findings in 1D raise interesting questions about the phases in the full 2D Lieb lattice which we show can be explored in current experiments.
Phase, AC conductivity and dielectric properties of Indeno[1,2-b]flourene-6,12 dione thin film as a function of frequency and temperature
Authors: El-Denglawey A , Qashou Saleem I , Darwish A A A , El-Zaidia E F M
Published: April 2021

Indeno [1,2-b] fluorene-6,12dione (Indeno-fluorene) films were deposited on glass substrates by thermal evaporation technique. x-ray diffraction of the Indeno-fluorene films shows amorphous phase nature. Alternating current, AC conductivity was studied as a function of frequency and temperature within a range of 40 Hz-8 MHz and 303–423 K, respectively. The calculated value of the electron density of states (N(EF)) near the Fermi states at room temperature and frequency of 500 kHz was 8.73 × 1023 eV−1cm−3. In addition, parts of dielectric constant-real and imaginary were investigated at different temperatures. The relaxation process, relaxation time, activation energy, Coulomb height potential, and the extensive localized electronic states were studied. The normalization spectra of electric modulus elucidate that Indeno-fluorene thin films can be expounded by a non-Debye type of relaxation. The obtained data were discussed in terms of correlated barrier hopping model (CBH) and candidate Indeno-fluorene films for solar cells, transistor units, and electronic applications.
IceCube constraints on violation of equivalence principle
Authors: F.G. Fiorillo Damiano , Mangano Gianpiero , Morisi Stefano , Pisanti Ofelia
Published: April 2021

Among the information provided by high energy neutrinos, a promising possibility is to analyze the effects of a Violation of Equivalence Principle (VEP) on neutrino oscillations. We analyze the recently released IceCube data on atmospheric neutrino fluxes under the assumption of a VEP and obtain updated constraints on the parameter space with the benchmark choice that neutrinos with different masses couple with different strengths to the gravitational field. In this case we find that the VEP parameters times the local gravitational potential at Earth can be constrained at the level of 10-27. We show that the constraints from atmospheric neutrinos strongly depend on the assumption that the neutrino eigenstates interacting diagonally with the gravitational field coincide with the mass eigenstates, which is not a priori justified: this is particularly clear in the case that the basis of diagonal gravitational interaction coincide with the flavor basis, which cannot be constrained by the observation of atmospheric neutrinos. Finally, we quantitatively study the effect of a VEP on the flavor composition of the astrophysical neutrinos, stressing again the interplay with the basis in which the VEP is diagonal: we find that for some choices of such basis the flavor ratio measured by IceCube can significantly change.
When will an elevator arrive?
Authors: Feng Zhijie , Redner S
Published: April 2021

We present and analyze a minimalist model for the vertical transport of people in a tall building by elevators. We focus on start-of-day operation in which people arrive at the ground floor of the building at a fixed rate. When an elevator arrives on the ground floor, passengers enter until the elevator capacity is reached, and then they are transported to their destination floors. We determine the distribution of times that each person waits until an elevator arrives, the number of people waiting for elevators, and transition to synchrony for multiple elevators when the arrival rate of people is sufficiently large. We validate many of our predictions by event-driven simulations.
Nonsingular matrix as private key on ElGamal cryptosystem
Authors: Maxrizal  , Irawadi Syafrul
Published: April 2021

The ElGamal cryptosystem is an asymmetric cryptosystem using commutative algebra. Currently, applications of commutative algebra are very vulnerable to attack. For this reason, some experts have developed a public-key cryptosystem based on non-commutative algebra. This study proposes the ElGamal cryptosystem using a matrix as the private key to guarantee the non-commutative algebra concept. The result of the cryptosystem is still working on a matrix of a specific size. The results show that we can modify the key generating algorithm, encryption, and description algorithms so that the proposed system can work.
Classification of Damaged Road Types Using Multiclass Support Vector Machine (SVM)
Authors: Sulistyaningrum D R , Putri S A M , Setiyono B , Ahyudanari E , Oranova D
Published: April 2021

Damage roads had been disturbed by social activities and involved in traffic accidents. Identification and classification of the types of defected road are required to minimize its impact and before repairs. Digital image processing technology can identify and classify the type of damaged roads automatically. In this study, the classification of defected roads is automatic with a multiclass Support Vector Machine(SVM). There are three classes in the classification process, namely, alligators, potholes, and cracks. The process of recognizing defected roads uses a multiclass SVM classification model with polynomial and Gaussian kernel function and One Vs. All strategy and uses a cell size of 16 × 16 pixels during the Histogram of Oriented Gradients (HOG) feature extraction process. and produces an accuracy value of 78,85%.
Similarity Transformation of Discrete Part Production Lines
Authors: Chen Hui , Li Lei , Zhang Zhichao
Published: April 2021

In order to improve the computational efficiency of models of production lines with unreliable machines, we propose the similarity transformation method by adjusting the design parameters, such as times between machine failures, times to repair and buffer capacities, in an equal proportion. It is found that the system throughput remains almost unchanged under the similarity transformation. The typical manufacturing system, serial production line, is taken as an example to verify the proposed method. Theoretical analysis and numerical experiments have been performed to confirm the feasibility and effectiveness of the method. The results show that the throughput error is no more than 5% and the calculation time is much less than that of the original model. Therefore, it is helpful to apply the similarity transformation method to large production line models to reduce computational complexity.
Temperature Regulation of Photovoltaic Cells using Phase Change Material Heat Sinks Integrated with Metal Foam
Authors: Al-Migdady Ahmad K.
Published: April 2021

This article investigates the cooling performance of Phase Change Material “PCM”-heat sinks integrated with porous metal that are attached to PV cells. Numerical simulations were carried out for a 2-dimensional configuration of a PCM-based heat sink subjected to uniform heat flux of 900W/m2 on the upper side and heat convection takes place at all other sides with a uniform convective heat transfer coefficient of 10 W/m2.°C. Two different PCMs were considered (n-Eicosane and RT44HC) and three values of metal foam porosity “e” were chosen as well (ε = 1.00, 0.97 and 0.90, where ε = 1.00 refers to no-metal foam case). Results showed that addition of metal foam enhances the cooling performance of PCM-based heat sinks. In the n-Eicosane based heat sinks, the PV-surface temperature was reduced by 6.31 °C and 7.00 °C for the 97% and 90% porosities respectively when compared to the no-metal foam case (100% porosity). On the other hand, in the RT44HC based heat sinks the PV-surface temperature was reduced by 5.50 °C and 6.15 °C for the 97% and 90% porosities respectively when compared to the no-metal foam case (100% porosity).
Numerical Simulation of Kinetic Kill Vehicle Impacting Biological Submunition Payloads
Authors: Zan Yang , Zheng Yuan-feng , Liu Zhen-yang , Cai Yi-qiang , Wang Hai-fu , Guo Huan-guo
Published: April 2021

Damage behavior of biological submunition payloads directly impacted by Kinetic Kill Vehicle (KKV) is studied by numerical simulation based on Autodyn-3D software. Target characteristics and structure equivalent model of the biological submunition payload and KKV are analyzed and obtained. Three factors including hit-point position, strike angle and KKV’s diameter are chosen to study the damage behavior. Three types of damage behaviors of biological submunitions, including deformation, partial disintegration and completely disintegration occur in simulation. As for influencing factors, hit-point position has little influence on damage effect when hit-point is not at either ends. While number of damaged submunitions firstly increases and then decreases with increasing of strike angle when hit-point is near the center of the submunition payload. For the given KKV, number of damaged submunitions increases significantly at the strike angle of 60° compared with the vertical impact. With increasing of the KKV’s diameter, number of completely disintegrated submunitions increases dramatically and the damage degree and deformation range of the payload skin gradually increases. Research in this paper could provide useful references for the optimization structural of KKV, selection of terminal encounter condition, and assessment of kinetic midcourse anti-missile interception.
Numerical Simulation of the Effects of Strain Hardening Exponent with and without Strain Rate Sensitivity of Material on Normal Elastic Plastic Impact
Authors: Kriflou Taoufik , Rachik Mohamed , Azrar Lahcen , El Bikri Khalid
Published: April 2021

The material behavior selection is an important factor governing the structural response analysis of transverse impact problems, such as impact force, indentation and local elastic plastic deformation. In the present paper, the effects of strain hardening exponent (n) and strain rate sensitivity (m) on the transient response were investigated for low impact velocity by the aid of finite element simulation using the Abaqus Software. Investigated parameters are impact force histories, indentation and plastic strain (PEEQ). Results showed that the effect of n values on required parameters is more pronounced, unlike strain rate sensitivity which has not a significant influence. As well, material behavior selection is essential for an accurate local plastic strain analysis.
Computational Modeling of the Corrosion Process and Mechanical Performance of Biodegradable Stent
Authors: Tao JiaYu , Cheng Jie , Zhao GuTian , Hu Xue , Gu XingZhong , Su JunJie
Published: April 2021

Magnesium alloy stents have drawn increasing research interest in recent years owing to their biodegradable behaviors. As dissolved by corrosion, mass of the magnesium alloy stents decreases with time, allowing mechanical load to gradually transfer to the surrounding tissues. This work aimed to develop a numerical model based on Continuum Damage Mechanics (CDM) combining pitting corrosion and stress corrosion crack to better predict the degradation behavior of biodegradable magnesium alloy stent. It was applied in coronary stents through finite element method compared with the use of single pitting corrosion model. The results indicated that addition of stress corrosion attack accelerated the degradation rate and support performance loss of stent compared with single pitting corrosion. The proposed model would bring new sights to simulation and serve the design of magnesium alloy stents.
Research on the Feasibility Verification Based on Continuous Vortex Ring Generator and the Matching Degree of Device Parameters
Authors: Tian Hao-Yu , Xu Lin , Hou Bao-Shen , Huang Tao , Huang Xin-Tong , Liu Jia-Qi , Dai Lu , Wu Yong-Jia
Published: April 2021

This paper proposes a new type of continuous vortex ring generator, which can significantly increase vortex ring generators’ ventilation by studying the matching degree of device parameters. This paper uses the model proposed by Gharib analysis, and the dimensionless circulation of the vortex ring measured by the vortex profile method to explore the properties of the vortex ring. In this paper, by studying the generation principle of a vortex ring in which a dynamic fluid flows through mechanical drainage and alternately ejected from a tapered spout and an annular spout, explore the best conditions for the continuous vortex ring. The research results show that a section of static fluid with a radial restriction is driven by the same dynamic fluid with a certain speed, and the fluid-carrying capacity of the vortex ring increases as the length to diameter ratio increases, after reaching a certain length no more noticeable change. An annular spout is equipped with a guide cylinder, and its clearance coefficient is within a specific reasonable range. When the annular spout ejects an airflow whose length-to-diameter ratio is in a specific functional relationship with the clearance coefficient, a high-quality vortex ring can be produced.
Thermal Environment Control of Buildings using Installation of Plants and Metal Panels on Brick Walls
Authors: Ornam Kurniati , Triyadi Sugeng , Wonorahardjo Surjamanto , Sutjahja Inge M. , Martonohadi Prameswara , Assegaf Sufiyah , Kimsan Masykur
Published: April 2021

One of the thermal behaviors of bricks on building walls might store heat in large amounts and delay it to be re-released. This performance will consequently prevail over the building’s environment, comprising the Urban Heat Island (UHI) phenomenon. Hence mitigation technology for controlling and managing heat gain is required to reduce the effect of UHI. Various research has studied this phenomenon mainly from orientation and the several types of wall insulation for sundry types of climates. However, it has not been significantly scrutinized from the green wall and metal panel wall viewpoint. This study aims to discern the thermal behavior of regular building brick walls using 3 (three) types of walls, i.e., conventional brick walls, metal-panel wall technology such as Aluminum Composite Panel (ACP) without air gap, and green walls technology by planting the vines in a trellised container with a sandy loam substrate. ENVI-met V4 software is performed for simulation by modeling a house building measuring 8 meters long, 6 meters wide, and 5 meters high. Metal panels and green walls are installed on all brick walls on the building’s west and east sides. The parameter observed was the surface temperature of walls and the air temperature pattern by introducing fixed wind speed (0,1 m/s). In the daytime, the results showed that using the technology intervention with ACP provided better results in terms of lower surface temperature than other types with a 0,6 – 6,7 % difference due to its conductive properties in storing heat. Moreover, green wall intervention utilizing vegetation yields better performance in the nighttime with a 0,3 – 3% difference as the Ivy Hadera is holding the heat during that time. Green wall intervention also evinces significant temperature rising at 09.00 – 16.00 since the Ivy Hadera vegetation has relatively sparse leaf space; hence there is a considerable amount of heat radiation reaching through the walls, and there is evapotranspiration of the vegetation causing heat release to the atmosphere.
Thermal Comfort Of The Outdoor Transition Space In the Dean’s Office Building
Authors: Ramawangsa Panji Anom , Prihatiningrum Atik , Seftyarizki Debby
Published: April 2021

The increase in the transmission of the COVID-19 disease, creating an effort to prevent transmission by controlling total of space users in the Dean’s Office Building, University of Bengkulu to avoid overcrowding users of space in buildings. The control has an impact on the increasing number of space users in the transition space of outdoor (terraces, hallways, corridors) in the eight Dean’s Office Buildings. The thermal comfort of the outdoor transition space needs to be considered because the post-pandemic adaptation behavior causes the change in the function of the transition area as buffer between outdoor and indoor spaces, is currently becoming a waiting room for entering buildings with uncertain waiting times. In addition, University of Bengkulu is located in coastal area with air temperatures during the day between 30 °C- 34 °C and wind speed ranging from 0-2,2 m/s. The purpose of this research is to determine the perception of thermal comfort of space users in the transition space, Dean’s Office Building, University of Bengkulu. Measurement data in the form of air temperature, air humidity, and wind speed at the peak of the dry month were carried out at 08.00-16.00 for 10 working days and interview data on the perception of thermal comfort of space users. Interview and measurement data will be inputted on the Ray-man measuring instrument to obtain the PET, PMV, SET values.
Development of Green Building Ranking Based on Stakeholders Values Using the AHP
Authors: Muchlis Aulia Fikriarini , Larasati Dewi , Sugeng Triyadi S , Hanifah Yulita , Wardhani Anedya , Ekawati Novya
Published: April 2021

Green buildings conserve precious natural resources and increase our standard of living. Green building, in principle, seeks to reduce the negative impact on our atmosphere and natural environment. This effort is marked by the existence of a green building rating. However, currently, not many construction stakeholders have used this rating system. Therefore, this paper attempts to illustrate the critical points of the green building concept based on stakeholder knowledge and, at the same time, offers new ranking criteria. This paper then chooses a general analytic approach, including literature on green buildings’ ranking and Indonesian religious values. AHP was selected as a method in this study to provide an overview of how much stakeholder confidence for spiritual values in green criteria. This study shows different weight values on the requirements for green buildings based on religious values and Greenship. Most of the stakeholders chose the Water criterion at 27.66% as a substantial point value for realizing a sustainable site, while in Greenship, almost all the criteria have the same weight. Confidently, the criteria and value weights used in realizing a sustainable site align with religious values because the implementation will be more straightforward.
Energy Efficiency in Church Building Based on Sefaira Energy Use Intensity Standard
Authors: Nabilah Aisyah , Devita Hanna Putri , Halen Yohannes Van , Jurizat Aldissain
Published: April 2021

The occupancy for buildings with religious purposes has infrequent periods of use that are near full occupancy to minimal or no occupancy. Thus, energy usage in buildings such as churches has lower overall energy intensity than other commercial buildings. The purpose of this study aims to analyze the use of energy in a church building by using Sefaira extension in SketchUp modeling application and to provide solutions so that the building’s Energy Use Intensity (EUI) value can be within Sefaira standard. This research was conducted by simulating a church building model into Sefaira application, which includes aspects of the assessment, namely building orientation, wind, openings, and material. This study describes the energy efficiency of buildings by changing the materials that are more optimal to respond to the heat received by the building. Changes applied to buildings by optimizing materials such as the application of insulations, ventilation, and solar screen reduce the value of Solar Heat Gain Coefficient (SHGC). This change significantly reduces the energy consumption from 125 kWh/m2/yr to 67 kWh/m2/yr in the building.
Estimation of energy consumption efficiency in office rooms cooling systems to create thermal comfort for the user
Authors: Lisa N P , Zuraihan Z , Fernand R , Siska D
Published: April 2021

Conservation and energy efficiency in air conditioning systems are very relevant to be conducted to increase efficiency and save energy as an effort to reduce energy consumption in buildings and reduce the formation of CO2 gas emissions, which are one of the main causes of increasing environmental temperature. Offices and settlements have a quite large dependence on energy. At the office, for instance, the spatial comfort greatly affects the user’s mood and the quality of work produced. Air conditioning or air controlling system is an effort to process the air to control room temperature, relative humidity, air quality, and its refreshment to maintain comfort requirements for room users. The purpose of this research was to assess the measurement of energy consumption used in the office of three floors and to respond to energy consumption savings that are used as an effort to yield efficient energy use, especially in air conditioning systems. The research method used is the Ecotect v.5 simulations, with the characteristics of a closed office space model and full of air conditioning throughout the rooms. The energy consumption in a room cooling system was calculated by using SNI 6196-2011. The amount of heat energy accumulated in each room, which is influenced by solar radiation, space leveling, activity, and lighting was also measured. By calculating the temperature distribution in the space of each floor by comparing the Ecotech v.5 simulation results with the existing EEI (Energy Efficient Index) field measurements generated by 46.22 kWh/H/m2/day based on the calculation of working operational hours, it was assumed that 8 hours/day with real operational 2920 hours/year and the total energy consumption of 16330 kWh/year were considered as a very wasteful criterion. The temperature on each floor differs from 26.8°C to 29°C, the difference between the simulation calculation and the existing measurement was 0.78°C, with an average temperature of simulation result was 27.53°C, the existing was 26.75°C. Besides, the temperature obtained was different in each room, this was influenced by the room orientation to the sun which affected the comfort level of the room