bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte Carlo study of Cu precipitation in bcc-Fe: temperature-dependent cluster expansion versus local chemical environment potentials
Authors: Redermeier A , Kozeschnik E
Published: February 2021

Phase decomposition in binary Fe1−x
Cu
x
is studied using Monte Carlo simulations. Initially, density functional theory calculations are utilized to determine reference energies of various Fe–Cu compounds that serve as input for a temperature and composition-dependent cluster expansion. On this basis, the thermodynamic properties of the bcc Fe–Cu system are predicted and used to simulate the equilibrium constitution of bcc Cu-rich precipitates in an Fe-rich solid solution at various temperatures and supersaturations. Complementarily, computationally efficient pair potentials are developed in the local chemical environment approach that are calibrated on the first principles-cluster expansion results. These are then utilized in large-scale simulations for analysis of the multi-particle precipitate evolution. It is concluded that both approaches provide comparable information in terms of the precipitate radius as well as interface constitution. Whereas the cluster expansion (‘full-information’) path is especially useful in predicting energies of various ground state configurations for small systems, the local chemical environment approach (‘fast-computation’) path is particularly useful in evaluation of cluster formation kinetics and evolution statistics.
The microstructural refinement and performance improvement of a nanoporous Ag/CeO2 catalyst for NaBH4 oxidation
Authors: Ma Chen , Wen Yang , He Gege , Wang Liqun , Gao Lumei , Sun Zhanbo
Published: February 2021

In this paper, Cu and Ce were added to melt-spun Al–Ag precursor alloys to refine the microstructures of nanoporous Ag and Ag/CeO2 composite catalysts for NaBH4 oxidation. After the precursor alloys were dealloyed in 20% NaOH, calcined in air and corroded again in 50% NaOH, Ag2Al in the precursor alloys was completely removed, and refined nanoporous Ag could be obtained; from this process, the finest microstructures were exhibited by Al84Ag8Cu8. When more than 0.3% Ce was added to the Al84Ag8Cu8 ribbons, a refined nanoporous Ag material that consisted of CeO2 nanorods interspersed between Ag ligaments was obtained. Electrochemical measurements indicated that the catalytic properties were clearly increased due to the Cu addition to the Al–Ag alloy. After Ce was added to the Al84Ag8Cu8 ribbons, the catalytic properties of the resulting material were further improved. In regard to melt-spun Al84Ag8Cu8Ce0.5, the obtained nanoporous Ag/CeO2 presented the best properties, and its current density was 2.5 times that of Al84Ag8Cu8, 3.1 times that of Al90Ag8Cu2 and 2.3 times that of Ag/Ce from the Al79Ag15Ce6 precursor alloy without Cu. It was believed that the core–shell structure composed of Ag and Cu-rich phases formed during dealloying could limit the diffusion of Ag and prevent the coarsening of Ag ligaments. Thus, the refined microstructures could provide a large specific surface or additional active sites for the catalytic reaction. Strong interactions resulted from the many interfaces between the Ag ligaments and interspersed CeO2 nanorods, and the more effective utilization of Ag was due to the decomposition of Ag2Al; this result was the key reason for the clear improvement in catalytic performance.
Positron range-free and multi-isotope tomography of positron emitters
Authors: Beekman F J , Kamphuis C , Koustoulidou S , Ramakers R M , Goorden M C
Published: February 2021

Despite improvements in small animal PET instruments, many tracers cannot be imaged at sufficiently high resolutions due to positron range, while multi-tracer PET is hampered by the fact that all annihilation photons have equal energies. Here we realize multi-isotope and sub-mm resolution PET of isotopes with several mm positron range by utilizing prompt gamma photons that are commonly neglected. A PET-SPECT-CT scanner (VECTor/CT, MILabs, The Netherlands) equipped with a high-energy cluster-pinhole collimator was used to image 124I and a mix of 124I and 18F in phantoms and mice. In addition to positrons (mean range 3.4 mm) 124I emits large amounts of 603 keV prompt gammas that—aided by excellent energy discrimination of NaI—were selected to reconstruct 124I images that are unaffected by positron range. Photons detected in the 511 keV window were used to reconstruct 18F images. Images were reconstructed iteratively using an energy dependent matrix for each isotope. Correction of 18F images for contamination with 124I annihilation photons was performed by Monte Carlo based range modelling and scaling of the 124I prompt gamma image before subtracting it from the 18F image. Additionally, prompt gamma imaging was tested for 89Zr that emits very high-energy prompts (909 keV). In Derenzo resolution phantoms 0.75 mm rods were clearly discernable for 124I, 89Zr and for simultaneously acquired 124I and 18F imaging. Image quantification in phantoms with reservoirs filled with both 124I and 18F showed excellent separation of isotopes and high quantitative accuracy. Mouse imaging showed uptake of 124I in tiny thyroid parts and simultaneously injected 18F-NaF in bone structures. The ability to obtain PET images at sub-mm resolution both for isotopes with several mm positron range and for multi-isotope PET adds to many other unique capabilities of VECTor’s clustered pinhole imaging, including simultaneous sub-mm PET-SPECT and theranostic high energy SPECT.
Method for estimating charge breeder ECR ion source plasma parameters with short pulse 1+ injection of metal ions
Authors: Angot J , Luntinen M , Kalvas T , Koivisto H , Kronholm R , Maunoury L , Tarvainen O , Thuillier T , Toivanen V
Published: February 2021

A new method for determining plasma parameters from beam current transients resulting from short pulse 1+ injection of metal ions into a charge breeder electron cyclotron resonance ion source has been developed. The proposed method relies on few assumptions, and yields local values for the ionisation times

1
/

n

e

σ
v

q
→
q
+
1

inz

, charge exchange times

1
/

n

0

σ
v

q
→
q
−
1

cx

, the ion confinement times τ

q
, as well as estimates for the minimum plasma energy contents

n

e

E

e

and the plasma triple products

n

e

E

e

τ

q

. The method is based on fitting the current balance equation on the extracted beam currents of high charge state ions, and using the fitting coefficients to determine the postdictions for the plasma parameters via an optimisation routine. The method has been applied for the charge breeding of injected K+ ions in helium plasma. It is shown that the confinement times of K
q+ charge states range from 2.

6

−
0.4

+
0.8

ms to 16.

4

−
6.8

+
18.3

ms increasing with the charge state. The ionisation and charge exchange times for the high charge state ions are 2.

6

−
0.5

+
0.5

ms–12.

6

−
3.2

+
2.6

ms and 3.

7

−
1.6

+
5.0

ms–357.

7

−
242.4

+
406.7

ms, respectively. The plasma energy content is found to be

2
.

5

−
1.8

+
4.3

×
1

0

15

eV cm−3.
Modeling of fast ionization waves in pure nitrogen at moderate pressure
Authors: Chen Xiancong , Zhu Yifei , Wu Yun , Hao Jinbo , Ma Xiaoguang , Lu Pengfei
Published: February 2021

The fast ionization wave (FIW) discharges in pure nitrogen in a capillary tube at 27 mbar, initiated by positive polarity, high-voltage nanosecond pulses, are numerically studied by coupled two-dimensional plasma fluid modeling. The 2D fluid code based on local mean energy approximation is validated and used, an extended three-exponential Helmholtz photoionization model is proposed for pure nitrogen. The development and structure of the nitrogen FIW is analyzed, the electric field and current are calculated compared with experimental measurements. The evolution of radial distribution of electrons and N2(C
3Π
u
) during the FIW development stage and in the afterglow are analyzed, the radial profiles of electron density show a ‘hollow’ structure in the FIW development stage, the temporal-spatial evolution of N2(C
3Π
u
) is dominated by the competition between the pooling reaction of

N

2

(

A

3

Σ

u

+

)

and the quenching by electrons. The role of photoionization on the nitrogen FIW radial morphology is discussed, the equivalent background electron density of photoionization in nitrogen discharge is suggested to be (4–6) × 1013 m−3. Spatial distribution of specific energy deposition (SED), fast gas heating (FGH) energy and temperature rise are obtained, heating efficiency varies with electric field E/N and SED and tends to be 10% at high SED. The dominating reactions responsible for FGH and their fractional contribution in space and time are analyzed, in the near axis region, pooling reactions of

N

2

(

A

3

Σ

u

+

)

and N2(B
3Π
g
) contribute up to 80% FGH energy, electron impact dissociation of molecular nitrogen contributes about 10%, while e-

N

2

+

recombination and quenching of N(2
D) atoms by N2 molecules contribute rest.
Tendon constrained inflatable architecture: rigid axial load bearing design case
Authors: Kim Ellen , Luntz Jonathan , Brei Diann , Kim Wonhee , Alexander Paul , Johnson Nancy
Published: February 2021

Inflatables can provide advanced functionality such as structural support, controlled compliance, posability, self-actuation, etc when they are architecturally constrained. Unfortunately, some of the key benefits of inflatables, including their low architectural complexity and high deploy-and-stow capability, are typically adversely affected as functionalities become more sophisticated. A new architectural approach, a tendon constrained inflatable (TCI), is introduced to decouple functionality from deploy-and-stow capability. A TCI is a structure composed of a soft inflatable bladder with rigid end caps connected by inextensible internal constraint tendons. When a TCI is inflated, the tendons under pure tension impose constraints on the inflatable by pre-tensioning the TCI to be able to resist external loads, but when not pressurized, the soft bladder and flexible tendons collapse and provide a compact stow. This paper develops the fundamental case of TCI functionality, rigid axial load bearing, by providing predictive models, validation experiments, design space plots, and a design case study. A model predicting the rigid load-bearing capacity as a function of pressure for varying TCI architectural design parameters is derived through (a) an unconstrained inflation model, based on an axisymmetric nonlinear membrane deformation model and a hyperelastic material model, and (b) a constraint model that bounds specific inflation directions depending on the applied constraint. This axial rigid load-bearing TCI performance model is validated through experiments measuring TCI deformation due to pressure and external load. This model serves as the basis to develop versatile design space plots that provide various views of the design parameter dependencies. These plots are demonstrated in the context of a deployable modular support design case study. The insights gained enable the design of TCIs with rigid load-bearing functionality in a deployable and stowable package as well as setting the foundation to develop more sophisticated architecture with decoupled functionality and deploy-and-stow capability.
Mean exit time for diffusion on irregular domains
Authors: Simpson Matthew J , VandenHeuvel Daniel J , Wilson Joshua M , McCue Scott W , Carr Elliot J
Published: February 2021

Many problems in physics, biology, and economics depend upon the duration of time required for a diffusing particle to cross a boundary. As such, calculations of the distribution of first passage time, and in particular the mean first passage time, is an active area of research relevant to many disciplines. Exact results for the mean first passage time for diffusion on simple geometries, such as lines, discs and spheres, are well-known. In contrast, computational methods are often used to study the first passage time for diffusion on more realistic geometries where closed-form solutions of the governing elliptic boundary value problem are not available. Here, we develop a perturbation solution to calculate the mean first passage time on irregular domains formed by perturbing the boundary of a disc or an ellipse. Classical perturbation expansion solutions are then constructed using the exact solutions available on a disc and an ellipse. We apply the perturbation solutions to compute the mean first exit time on two naturally-occurring irregular domains: a map of Tasmania, an island state of Australia, and a map of Taiwan. Comparing the perturbation solutions with numerical solutions of the elliptic boundary value problem on these irregular domains confirms that we obtain a very accurate solution with a few terms in the series only. MATLAB software to implement all calculations is available at https://github.com/ProfMJSimpson/Exit_time.
Application of feedforward predictive control in DC furnace coordination system
Authors: DENG Zhiguang , Zhengxi HE , Biwei ZHU , Jialiang ZHU , Xin LV , Qian WU
Published: February 2021

In order to solve the control difficulties such as large dynamic delay, serious coupling between machine and furnace and strong nonlinear, the feedforward and feedback predictive control is proposed to control the coordinated system on the basis of multi-model predictive control, and the static feedforward part designs the feed line feedforward of coal quantity against coal quality disturbance on the basis of the accurate balance of energy. Thus, the reference total fuel quantity under the target load instruction is determined, and the dynamic part fully considers the dynamic compensation of the unit energy storage, gives a certain overshoot fuel quantity to the boiler regulation, speeds up its response, and ensures the rapidity of the unit. The real-time simulation results of virtual DPU (Distributed Processing Unit) show that the designed feedforward-feedback predictive control can quickly respond to load change, improve the resistance to fuel disturbance, reduce the fluctuation of main steam pressure, and better ensure the safe, economic and stable operation of the coordination system.
Design of formaldehyde concentration detection system for smart home based on STM32 controller
Authors: Liu Meili , Zhang Caizhong
Published: February 2021

It is a well-known thing that formaldehyde can seriously endanger human health. During decoration, some decoration materials, including furniture, will contain a large amount of formaldehyde, and some wall paint will also emit a lot of formaldehyde. Therefore, how to judge that the harmful gas in a house exceeds the standard has become a headache. In response to this problem, this article has designed an intelligent formaldehyde detection system, which can accurately detect the concentration of harmful gases in the room and then alarm. The operation is simple.The system consists of STM32F103C8T6 microcontroller circuit, LCD1602 liquid crystal display circuit, and formaldehyde detection sensor circuit. The voltage value and formaldehyde concentration value before formaldehyde conversion can be displayed in real time as the formaldehyde concentration changes. If the concentration of formaldehyde in the air is higher than the body’s tolerance range, the buzzer will sound a “beep” alarm, otherwise it will not sound.
A FPGA-based end-to-end acceleration framework for fast deployment of Convolutional Neural Networks
Authors: Zhang Lin , Li Bing , Liu Binfeng
Published: February 2021

Nowadays, CNNs has delivered the state-of-the-art performance in the field of computer vision, image classification, etc. As CNNs going deeper, it becomes more difficult to implement CNNs applications based on general-purpose computing platforms. Recently, many FPGA-based CNNs accelerators have been proposed, these accelerators achieved high performance on specific CNNs models, however they are somewhat lack of reconfigurability to fit different applications. To deal with this problem, an end-to-end acceleration framework was proposed in this paper, which consists of a parameterized hardware accelerator and a fully automatic software framework. Parallel computation and pipeline optimization are deployed in the hardware design to achieve high performance. Simultaneously, runtime reconfigurability is implemented by using a global register list. By encapsulating the underlying driver, a three-layer software framework is provided for users to deploy their pre-trained models. A typical CNNs model used for handwritten digital recognition was selected to test and verify the accelerator. The experimental result shows that the accelerator can reach a recognition speed of 22.65FPS under the clock frequency of 100MHz, comparing with ARM Cortex-A9 working at 650MHz, it can achieve 25.9 times of acceleration effect, with only 1.59W power consumption.
System identification and adaptive control of micro helicopter
Authors: Xu Weixiong , Zhang Fubiao , Lin Defu
Published: February 2021

This paper copes with the controller design problem of a micro helicopter, which is a multivariable and strongly coupled nonlinear system. The state-space model near the hovering condition of pitch and roll channels is acquired by least-square system identification method, with flight test verification. Based on the identified model, model reference adaptive control is designed as angular rate controller, and PID controller is used to stabilize attitude loop. State-space model helps to decouple the roll and pitch channels, and model reference adaptive control can address external disturbances, model uncertainties and nonlinearities of the dynamics, which can be estimated and further eliminated online. Eventually, both simulations and actual flight tests are conducted to verify the effectiveness of the proposed control scheme.
Evaluation of an error correction function using correlation characteristics of spread codes in CDMA-based transmission methods
Authors: Mochizuki Hiroshi , Nakamura Hideo
Published: February 2021

In previous researches, we have proposed novel modulation methods such as the CDMA-QAM method in which Code-Division Multiple Access (CDMA) and Quadrature Amplitude Modulation (QAM) are combined, and applied these methods for improvement of railway signalling systems. Although a rail is used as a transmission medium, there are severe conditions for transmission, such as strong attenuation at frequencies above about 10 kHz. To overcome this restriction, we attempted to improve the S/N characteristics in our proposed method. Specifically, we focused on correlation characteristics of spread codes which are used in CDMA. In this paper, we show that an error correction function that does not require additional bits for such correction can be realized by using the correlation characteristics. We evaluated the effectiveness of this correction method and conducted computer simulations in which the method was employed for CDMA-based transmission.
Biocompatibility of nanomaterials and their immunological properties
Authors: Kyriakides Themis R , Raj Arindam , Tseng Tiffany H , Xiao Hugh , Nguyen Ryan , Mohammed Farrah S , Halder Saiti , Xu Mengqing , Wu Michelle J , Bao Shuozhen , Sheu Wendy C
Published: February 2021

Nanomaterials (NMs) have revolutionized multiple aspects of medicine by enabling novel sensing, diagnostic, and therapeutic approaches. Advancements in processing and fabrication have also allowed significant expansion in the applications of the major classes of NMs based on polymer, metal/metal oxide, carbon, liposome, or multi-scale macro-nano bulk materials. Concomitantly, concerns regarding the nanotoxicity and overall biocompatibility of NMs have been raised. These involve putative negative effects on both patients and those subjected to occupational exposure during manufacturing. In this review, we describe the current state of testing of NMs including those that are in clinical use, in clinical trials, or under development. We also discuss the cellular and molecular interactions that dictate their toxicity and biocompatibility. Specifically, we focus on the reciprocal interactions between NMs and host proteins, lipids, and sugars and how these induce responses in immune and other cell types leading to topical and/or systemic effects.
Spectral curves of hyperbolic monopoles from ADHM
Authors: Sutcliffe Paul
Published: February 2021

Magnetic monopoles in hyperbolic space are in correspondence with certain algebraic curves in mini-twistor space, known as spectral curves, which are in turn in correspondence with rational maps between Riemann spheres. Hyperbolic monopoles correspond to circle-invariant Yang–Mills instantons, with an identification of the monopole and instanton numbers, providing the curvature of hyperbolic space is tuned to a value specified by the asymptotic magnitude of the Higgs field. In previous work, constraints on ADHM instanton data have been identified that provide a non-canonical realization of the circle symmetry that preserves the standard action of rotations in the ball model of hyperbolic space. Here formulae are presented for the spectral curve and the rational map of a hyperbolic monopole in terms of its constrained ADHM matrix. This extends earlier results that apply only to the subclass of instantons of JNR type. The formulae are applied to obtain new explicit examples of spectral curves that are beyond the JNR class.
Research on short-time Prediction of driving behaviour at unsignalized intersections based on machine learning
Authors: Zhang Yunfan , Yan Xuedong
Published: February 2021

The unsignalized intersections are the important nodes in the road network, and also the sections with a high incidence of serious collision accidents. Based on the driving simulation experiment, the interactive driving behaviours of multiple drivers were collected. The data were input to the machine learning model, training for predicting the short-time driver’s decision-making. The results showed that the Random Forest model has a better prediction effect than the Support Vector Machine (SVM) model, and the shorter prediction interval also has a better prediction effect. This study was helpful to give timely warning to drivers in danger and provided a new idea for the research of collision prevention warning strategies and control methods.
Study on emergency response model during construction of Sichuan-Tibet Railway
Authors: Cui Yunxiao , Zhi Danyue , Lv Ying
Published: February 2021

During the construction of The Sichuan-Tibet railway, there is a risk of sudden natural disasters. Rapid and effective rescue to the affected areas can reduce casualties and property losses. Based on the interval planning theory, this paper studies the emergency rescue plan in the construction of Sichuan-Tibet railway considering the coordinated rescue of various transportation modes. We constructs a two-stage model of distributing relief materials to the disaster areas and bringing the injured back to the facilities. In the first stage, the facility storage centre point responsible for rescue is decided, and the facility storage centre point opening scheme that conforms to the constraints of the actual time window is obtained. The second stage logistics vehicle distribution problem, to the disaster areas to deliver relief supplies and bring back the injured, the optimized distribution route plan. Finally, an example analysis is carried out to verify the feasibility of the model by solving GAMS.
Research on Guiding Technology for Ecological and Sate Driving of Vehicles
Authors: Wang Kun , Tian Na
Published: February 2021

Based on the vehicle-road coordination technology, the decision-making model of vehicle entering signalized intersection and the optimization model of eco-driving speed guidance are studied. Using vehicle speed guidance technology to provide drivers with guidance information can effectively reduce vehicle fuel consumption and enhance vehicle safety. This paper establishes an engine fuel consumption model based on power demand and an optimization model of vehicle speed guidance based on exponential function. Then conduct simulation tests on the energy-prioritized vehicle speed guidance optimization model designed in this paper and obtain the speed optimization curve under different traffic conditions. The test results show that after the vehicle is guided by the vehicle speed guiding model, its driving speed and acceleration are relatively smooth, which can effectively reduce the fuel consumption. When the initial speed is the same, the vehicle passes through the intersection just when the signal lamp changes. At this time, the fuel consumption of the vehicle is lower than the other guidance modes that meet the model and when the vehicle is properly accelerated, the fuel consumption rate has little effect. But at the time of deceleration, the fuel consumption rate suddenly changes and the fuel consumption increases rapidly.
Container slot allocation and dynamic pricing considering overbooking and market segmentation
Authors: Yu Mingzhu , Liao Jiajing
Published: February 2021

In this paper, we study the problem of slot allocation and dynamic pricing for container liner with uncertain demand. We consider the carrier’s overbooking strategy and market segmentation. A two-stage mathematical model is proposed for container liner slot allocation and dynamic pricing. After linearizing the model, CPLEX can be used to solve it. The results of numerical experiments show that the model considering both overbooking and market segmentation can significantly improve the revenue of container liner companies.
Study on Seismic Resistance and Isolation Method of Concrete Frame Structure
Authors: Wu Minhao
Published: February 2021

.Earthquake, as a natural phenomenon that can bring enormous energy, usually causes buildings collapses and has brought great losses to human beings in recent years, so seismic design is closely related to social stability and economic development. As a basic kind of building structure, frame has been prevalent in our daily life, so the seismic resistant design of frame structure becomes essential. This paper firstly introduces a preliminary understanding of this phenomenon of earthquake, analyzes the forms of damage of frame structures caused by earthquake, and then analyzes the updates of Chinese seismic design codes and the specific measures corresponding to earthquake hazards (shock absorber/damper, seismic isolation), finally makes a prospect for the development of seismic design in the future.
Optimization of earth gravity field model and its application in elevation fitting
Authors: Haicheng Zhu , Xidong Ma , Zhen Wang , Zhixiong Guo , Zhanying Luo
Published: February 2021

Based on the non-statistical theory, this paper proposes a new technique for the optimization of the earth gravity field model based on the maximum membership degree and the principle of information entropy, combined with the “removal and recovery” algorithm. On the basis of theoretical analysis, eight earth gravity field models were selected and 33 elevation points in the same region were selected. Combined with the new technology adopted in this paper, model optimization and precision analysis were carried out, and it was found that the model based on the optimal model was more suitable for elevation fitting. Further data analysis shows that the remove-recovery algorithm based on the optimal model can improve the feasibility of GPS elevation measurement in high-precision measurement.
Dynamic Evaluation Technology of Bridge Based on Multi-source Heterogeneous Data Fusion
Authors: Pang Rong , Yang Yan , Zhang Peng , Yuan Yuan , Yu Zhibin , Tang Guangwu , Sun Caizhi , Huang Aiguo , Han Kunlin , Jiang Yongquan , Liu Dayang
Published: February 2021

Based on the multi-source and heterogeneous characteristics of massive state sensing data of bridges, this paper establishes a multi-source heterogeneous bridge state sensing data feature extraction and analysis method. A dynamic evaluation model of bridge technology based on multi-source heterogeneous data fusion is proposed. For the first time, the relationship between multi-source perceptual data and bridge infrastructure technology is established, the knowledge graph of bridge infrastructure technology is constructed, and the relationship between various state-aware data and bridge technology is explicitly expressed by the map. This collaborative association is used to dynamically evaluate and predict bridge technology.
A time-varying distributed unit hydrograph and its application in flood simulation of small mountainous watersheds
Authors: Wang Yali , Mei Guodong , Wang Sha
Published: February 2021

Flood forecasting is an important non-engineering measure to reduce flood damage. Small mountainous watersheds are characterized by rapid flow concentration and steeply rising and falling floods. Their flow concentration process exhibits strong time dependence, which is not well-captured by conventional unit hydrographs. In this paper, four mountainous watersheds were studied, and an algorithm for generating a time-varying distributed unit hydrograph (TVDUH) was proposed. The algorithm was integrated with the China Flash Flood Hydrological Model (CNFF-HM) to simulate small watersheds in the study area. The results showed relatively large Nash-Sutcliffe efficiency (NSE) of about 0.8 for the watersheds during the calibration and validation periods. Then the TVDUH was compared with the time-invariant one. The results showed that the TVDUH could better reflected the flow concentration characteristics of small mountainous watersheds, as the method took into account the effect of rainfall intensity on flow concentration during the computation process. And the TVDUH has great application potential in flood forecasting in mountainous watersheds to reduce the loss of flood disasters.
Analysis on Security Risks in Tunnel Construction Based on the Fault Tree Analysis
Authors: Yang Ruijuan , Deng Yousheng
Published: February 2021

Since tunnel engineering, as a kind of underground construction, has huge security risks, it is very important to evaluate the safety risk of tunnel construction stage. It cannot only provide basis for risk control but ensure construction safety. Taking Qingpingchuan tunnel as an example, the WBS-RBS method is employed to identify the construction risk of the tunnel and the identified risk sources are used to analyzed qualitatively and quantitatively with fault tree theory. Finally, we can conclude that the critical factor affecting the collapse of Qingpingchuan tunnel is the instability of surrounding rock, and that the secondary critical factor lies in the inconsistence of the soil quality with the survey documents, low effect of waterproof and drainage facilities, weak strength of pre reinforcement, excessive steps of excavation cycle, unqualified support construction, inaccurate advanced geological prediction, etc.
Accident Causing Theory in Construction Safety Management
Authors: Chen Yijiao , Wang Zeming
Published: February 2021

The accident rate of construction industry has been very high, so the construction safety management is particularly important. Accident causation theory is a common theory, which can improve the safety management of construction. Based on this, this paper studies the application of accident causing theory in construction safety management. This paper compares the common accident causing theories, selects the relatively more advantageous “4M“ theory, applies it to the construction safety management, establishes the safety evaluation system, selects two unfinished projects in the construction site for analysis, and selects the safety fuzzy comprehensive evaluation model in the evaluation method. This study found that after applying the accident cause theory, the human factor index score of item 1 is 91, the material factor index score is 86, the management factor index score is 89, and the environmental factor index score is 91. The human factor index score of item 2 is 90, the material factor index score is 85, the management factor index score is 86, and the environmental factor index score is 88. The security of both projects has changed from general to safe. In this way, we know that the application of accident cause theory can effectively improve the safety of construction.
Application of circular anti slide pile with plum blossom arrangement in Expressway Engineering
Authors: Peng Wu Kun , Ying Sun , Ming Xing Zhu
Published: February 2021

By using the finite element numerical simulation method, the simplified Bishop method and strength reduction method are used to analyze the stability of a high slope which is protected and treated by anti slide pile combined with prestressed anchor cable grading scheme in Guangdong Province, and the similarities and differences between rectangular pile and plum shaped circular pile in slope treatment effect are compared. Through calculation and analysis of field measured data, it is proved that the circular anti slide pile with plum shaped layout has similar effect with the traditional rectangular anti slide pile, and has the advantages of high degree of mechanization construction and low construction safety risk, so it can be used as the alternative scheme of rectangular pile
The invulnerability assessment of two-layer railway network under the uncertain environmental hazard risk
Authors: Zhang Hanqing , Ma Xiaoping , Jia Limin , Zhao Ruhao , Tian Yin
Published: February 2021

The failure of the railway station or line will cause the reduction of the railway network efficiency and bring travel inconvenience to the passengers, especially for the key stations and tracks. Reasonable invulnerability assessment is beneficial to maintain the system operation ability and prevent passengers from abandoning railway when the uncertain environmental hazard risk is appeared. At present, larger numbers of research about the railway network invulnerability assessment are purely based on complex network theory, while ignored the nature of railways. In this paper, the Railway Network Invulnerability Model (RNIM) is introduced from the perspective of infrastructure network and service network, and the efficiency of the proposed RNIM is verified according to compare the structural connectively and functional accessibility using different attack strategies. Furthermore, the RNIM framework is applied on the China high-speed railway network, and the results show the validity of the proposed model for the invulnerability of railway network assessment in accurately and efficiently. Finally, some protection suggestions are proposed to reduce the negative effects after the inevitable disruptions emerged.
Experimental study of wave force on large steel plate cylinder structure
Authors: Lv Yingxue , Sun Yunjia
Published: February 2021

Steel plate cylinder is more and more widely used as breakwater and revetment structure, but the existing design codes related to breakwater lack the distribution of wave force on the outside of steel plate cylinder under the action of waves. In this paper, the 2-D wave physical model experiment is used to test the pressure distribution of large diameter steel plate cylinder structure under wave action. The results show the wave distributions along different cross sections of the facing side during the crest and trough action. It provides the necessary theoretical basis and technical support for the design of large diameter steel plate cylinder.
Research method of comprehensive geophysical exploration for urban covered karst
Authors: Yin Xiansong , Luo Xiaojie , Zhang Sanding
Published: February 2021

During engineering investigation of covered karst in cities via conventional drilling and geophysical exploration techniques, detection accuracy is highly affected by environmental conditions. In this paper, a karst investigation on an important municipal project in Wuhan is taken as example and the clue to study geophysical exploration of municipal covered karst is proposed: engineering investigation - choose of proper geophysical exploration method - geophysical exploration - drilling confirmation. In this clue, previous geotechnical investigation data should be fully used and based on the geological conditions, petro physical parameters and investigation purpose, comparison experiment was carried out among many geophysical exploration methods and then effective geophysical exploration method was selected to reduce unnecessary work load. Moreover, drilling holes were randomly chosen for verification. It proves that the result of karst study done by geophysical exploration method from experiment comparison is relatively in accordance with the actual karst development situation. The result can provide accurate and reliable basis for engineering designs.
Effect of particle size on the microstructure and tensile property of the Al-28.5Si alloy prepared by continuous powder extrusion
Authors: Yin Jiancheng , Li Yanfei , Niu Yingshuo , Zhang Zitan , Song Dan , Chen Yegao , Liu Yingli , Zhong Yi
Published: February 2021

Continuous powder extrusion, a new powder consolidation technology, is used to process alloy powders that are difficult to form. In the paper, Al-28.5Si alloys were successfully prepared by continuous powder extrusion, and the influences of particle size on the microstructure and tensile property have been investigated. In the as-extruded rods, the primary Si phase is dispersed in the α-Al matrix. As the powder size reduces from more than 75 μm to less than 25 μm, the equivalent diameter of the primary Si particles consecutively decreases, but the shape factor increases. Comparing the Si particles in the alloy rod and the powder, it is found that the eutectic Si phase disappears during continuous extrusion. Primary Si particles change from coarse and irregular to round. Specifically, the ultimate tensile strength and elongation at break of the powder-extruded alloy further increase from 211 MPa to 266 MPa and 0.99% to 2.21%. Moreover, the fracture mechanism of alloy rods is the brittle fracture.
Exact asymptotic behavior of pulsating traveling waves for a periodic monostable lattice dynamical system
Authors: Wu Shi-Liang , Chen Guang-Sheng , Hsu Cheng-Hsiung
Published: February 2021

This paper is concerned with the pulsating traveling waves of a periodic lattice dynamical system with monostable nonlinearity. We first establish the exponential upper and lower bounds of the pulsating wave profiles at minus infinity. Then we prove the uniqueness result and derive the asymptotic behavior of all non-critical monostable pulsating traveling waves. This might be the first time to obtain the exact asymptotic behavior of the pulsating traveling waves for periodic discrete systems towards the unstable steady state.
Prediction of Cardiovascular Disease Risk Accounting for Future Initiation of Statin Treatment
Authors: Xu Zhe , Arnold Matthew , Stevens David , Kaptoge Stephen , Pennells Lisa , Sweeting Michael J , Barrett Jessica , Di Angelantonio Emanuele , Wood Angela M
Published: February 2021

Cardiovascular disease (CVD) risk-prediction models are used to identify high-risk individuals and guide statin initiation. However, these models are usually derived from individuals who might initiate statins during follow-up. We present a simple approach to address statin initiation to predict “statin-naive” CVD risk. We analyzed primary care data (2004–2017) from the UK Clinical Practice Research Datalink for 1,678,727 individuals (aged 40–85 years) without CVD or statin treatment history at study entry. We derived age- and sex-specific prediction models including conventional risk factors and a time-dependent effect of statin initiation constrained to 25% risk reduction (from trial results). We compared predictive performance and measures of public-health impact (e.g., number needed to screen to prevent 1 event) against models ignoring statin initiation. During a median follow-up of 8.9 years, 103,163 individuals developed CVD. In models accounting for (versus ignoring) statin initiation, 10-year CVD risk predictions were slightly higher; predictive performance was moderately improved. However, few individuals were reclassified to a high-risk threshold, resulting in negligible improvements in number needed to screen to prevent 1 event. In conclusion, incorporating statin effects from trial results into risk-prediction models enables statin-naive CVD risk estimation and provides moderate gains in predictive ability but had a limited impact on treatment decision-making under current guidelines in this population.
Alcohol Reduction to Reduce Relapse in Acute Alcoholic Pancreatitis—Missed Opportunities
Authors: Sissingh Noor J , Umans Devica S , Goudriaan Anna E , Sijbom Martijn , Verdonk Robert C , van Hooft Jeanin E ,   for the Dutch Pancreatitis Study Group
Published: February 2021

Aim

Resuming drinking is a main contributant to recurrence in alcoholic pancreatitis. We assessed current clinical practice in the Netherlands regarding alcohol in managing patients with a first episode of acute alcoholic pancreatitis.

Methods

A survey was distributed to 35 hospitals affiliated with the Dutch Pancreatitis Study Group. We evaluated current support based on various components of brief interventions, the participation of psychosocial healthcare providers, the cooperation with the primary care physicians and the presence of a protocol and its implementation.

Results

The response rate was 100% (n = 35). Psychoeducation is the most frequently performed intervention in current support treatment (97% of hospitals). In 17% of hospitals, healthcare providers with a psychosocial background routinely participate in current support treatment; 37% of hospitals create an individual treatment plan in which goals regarding alcohol cessation are specified and only 46% of hospitals provide the primary care physician with specific discharge information; 31% of hospitals indicate that the treatment is uniformly performed within their division of Gastroenterology. Protocols are available in 3% of the hospitals surveyed. Opportunities to involve the patient’s social network were not given sufficient priority.

Conclusion

Among Dutch hospitals, there is no routine management strategy with regard to enhancing treatment for heavy alcohol use in alcoholic pancreatitis patients. There is a need to test a validated support program in randomized studies. Meanwhile, possible opportunities for effecting change are often missed.
Welding Fume Exposure and Health Risk Assessment in a Cohort of Apprentice Welders
Authors: Dueck Meghan E , Rafiee Ata , Mino James , Nair Sindhu G , Kamravaei Samineh , Pei Lei , Quémerais Bernadette
Published: February 2021

Welding fumes vary in composition depending on the materials and processes used, and while health outcomes in full-time welders have been widely studied, limited research on apprentices exists. Besides, few data are available for metals such as vanadium and antimony. This study aimed to look at individual metals present in welding fumes in the learning environment of apprentice welders. Forty-three welders and 41 controls were chosen from trade programmes at the Northern Alberta Institute of Technology. Ambient and personal air samples were collected at days 0, 1, 7, and 50 of their training and analysed for mass and metal concentrations using Inductively Coupled Plasma Mass Spectrometry. Results showed increases in particle and metal concentrations as apprentices progressed throughout their education and that concentrations at day 50 were similar to levels found in the literature for professional welders. Variable concentrations indicate that some individuals may not properly use the local exhaust ventilation system. Other possible explanation for variations are the position of the sampler on the shoulder, the time spent welding and in each welding position, and the skills of the welders. Strong relationships were observed between particle and metal concentrations, suggesting that these relationships could be used to estimate metal exposure in welders from particle exposure. Welding processes were the most important determinant of exposure in apprentice welders, with Metal Core Arc Welding producing the largest particle concentrations followed by oxyacetylene cutting, and Gas Metal Arc Welding. Health risk assessment showed that welder apprentices are at risk for overexposure to manganese, which suggests that professional welders should be monitored for manganese as they are exposed more than apprentices. Training in proper positioning of local exhaust ventilation system and proper use of respirators are recommended in training facilities.
One tree, many colonies: colony structure, breeding system and colonization events of host trees in tunnellingMelissotarsusants
Authors: Eyer Pierre-André , Vargo Edward L , Peeters Christian
Published: February 2021

Ants exhibit a striking variety of lifestyles, including highly specialist or mutualist species. The minute blind workers of the African genus Melissotarsus chew tunnels in live trees to accommodate their obligate partner scale insects. Their modified legs are adapted for tunnelling, but are unsuited for walking outside, confining these ants to their initial host tree. Here, we investigated whether this unique lifestyle results in complex patterns of genetic diversity at different scales, from the same tree to different populations. Using 19 microsatellite markers, we assessed their mating strategy and colony structure among and across populations in South Africa. We showed that only one queen reproduces within a colony, mated with up to three males. However, several inseminated dealate queens are present in colonies; one probably replaces the older queen as the colony ages. The reproduction of a single queen per colony at a given time results in genetic differences between colonies, even those located on the same tree. We discuss how the slow process of colony digging under the bark and the lack of workers patrolling above the bark might result in reduced competition between colonies and allow several secluded colonies to cohabit the cramped space on a single tree.
‘Just Get on with It’: A Qualitative of Study of Social Workers’ Experiences during the Political Conflict in Northern Ireland
Authors: Campbell Jim , Duffy Joe , Tosone Carol , Falls David
Published: February 2021

This article reports on a retrospective study of social workers experiences and perception of practice during the height of the political conflict in Northern Ireland (1969–1988). The article describes the qualitative research methodology used to access the sample, design of interview schedule and data collection. Data were analysed using an iterative process to highlight emergent themes. Interviews were carried out with twenty-eight social workers who were employed in a range of agencies. The findings explore how social workers routinely had to negotiate access to communities in the midst of this violence, sometimes through paramilitary organisations. Respondents identified a range of coping mechanisms that they had used to make the ‘abnormal normal’. This included adopting apolitical, neutral stances, yet taking risks in the everyday tasks of meeting the needs of individuals and families. There was, however, limited evidence of employers providing support for practitioners, with peer support most prevalent and purposive forms of education and training during this period. The authors argue for greater attention to the skills and knowledge required for interventions with victims and survivors of the conflict and a more holistic approach to the analysis of social work and political conflict across international contexts.