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As it involves the lightest physical states excited from the vacuum by the vector quark current, near-threshold $\rho^0$ photoproduction is considered a possible way to research the proton radius and the absolute value of the scattering lengths of the $\rho^0$--proton interaction. In this work, under the assumption of a scalar form factor of dipole form, the value of the proton mass radius is calculated as $0.85\pm 0.06 \text{ fm }$ by fitting the differential cross section of the $\gamma p \rightarrow \rho^0 p$ reaction at near-threshold energy. For light vector meson photoproduction, because the exchange of a scalar quark--antiquark pair is not suppressed and should dominate the scalar gluon exchange, the radius we extract from $\rho^0$ photoproduction is likely to represent the quark radius of the proton. This fact may explain why the value obtained in this work is very near the proton charge radius. Moreover, the absolute value of the $\rho^0$--proton scattering length $|\alpha_{\rho^0 p}|= 0.31 \pm 0.06 \text{ fm}$ is obtained for the first time within the vector meson dominance model. This result disobeys the rule that the absolute value of the vector meson and proton scattering length $|\alpha_{V p}|$ increases with the meson's mass, which can be attributed to treating the $\rho^0$ meson as a point in the analysis. These results provide useful theoretical information for an in-depth understanding of proton structure and the proton--vector meson interaction., Comment: 6pages, 6 figures. To be published in Science China Physics, Mechanics & Astronomy

Inspired by the recent Hall C and GlueX measurements of $J/\psi$ photoproduction, a systematic analysis of the contribution of quantum anomalous energy (QAE) to the proton mass is carried out under the framework of the vector meson dominance model. The results show that the effective Pomeron model and the parametrized two gluon exchange model can explain the cross section of $J/\psi$ photoproduction well. Based on the predicted cross section values given by the two models, the distribution of the QAE contribution with the energy is extracted for the first time. Finally, the average value of the QAE contribution is estimated to be (3.50$\pm$0.70)$\%$, which suggests that the QAE contribution to the proton mass is small. Accordingly, we compared this result with those of other groups and explored the causes for the differences., Comment: 8 pages, 9 figures

Element doping into the Cu2ZnSn(S,Se)4 (CZTSSe) absorber is an effective method to optimize the performance of thin film solar cells. In this study, the Cu2InxZn1-xSn(S,Se)4 (CIZTSSe) precursor film was deposited by magnetron cosputtering technique using indium (In) and quaternary Cu2ZnSnS4 (CZTS) as targets. Meanwhile, the In content was controlled using the direct current (DC) power on In target (PIn). A single kesterite CIZTSSe alloy was formed by successfully doping a small number of In3+ into the main lattice of CZTSSe. The partial Zn2+ cations were substituted by In3+ ions, resulting in improving properties of CZTSSe films. Morphological analysis showed that large grain CIZTSSe films could be obtained by doping In. The well-distributed, smooth, and dense film was obtained when the PIn was 30 W. The band gap of CIZTSSe could be continuously adjusted from 1.27 to 1.05 eV as PIn increased from 0 to 40 W. In addition, the CIZTSSe alloy thin film at PIn = 30 W exhibited the best p-type conductivity with Hall mobility of 6.87 cm2V−1s−1, which is a potential material as the absorption layer of high-performance solar cells.

(Na0.1Cu0.9)2ZnSn(S,Se)4 thin films with a single kesterite phase were synthesized using a sol-gel spin-coating method accompanied by rapid post-annealing. In this study, we investigated the effect of selenization time on the crystal quality and photoelectric performance of the (Na0.1Cu0.9)2ZnSn(S,Se)4 films. It was found that the crystallinity and morphology of the films was enhanced, and some of bigger Se substituted for the S site in (Na0.1Cu0.9)2ZnSn(S,Se)4 with increasing the selenization time. The bandgap of the film can be regulated from 1.04 eV to 0.99 eV by varying the selenization time. In addition, all films showed p-type conductive characteristics, and films with optimal electrical performance could be obtained by optimizing the selenization time. Finally, the (Na0.1Cu0.9)2ZnSn(S,Se)4 thin film with the best crystal quality and optical-electrical characteristics was obtained at an optimized selenization time of 15 min. A high power conversion efficiency (PCE) of 3.92% was obtained for the (Na0.1Cu0.9)2ZnSn(S,Se)4 device, which is 42% higher compared to that of the undoped Cu2ZnSn(S,Se)4 (CZTSSe) device.

In this work, the cross-section of the reaction $\gamma p \rightarrow V(J/\psi,\psi(2S)) p$ from the production threshold to medium energy is studied and systematically analyzed within two gluon exchange model. The obtained numerical results are in agreement with experimental data and other theoretical predictions. Under the assumption of the scalar form factor of dipole form, the value of proton mass radius is calculated as $0.55\pm 0.09$ fm and $ 0.77\pm 0.12$ fm from the fit to the predicted $J/\psi $ and $\psi(2S)$ differential cross-section, respectively. Finally the average value of proton mass radius is estimated to be $\sqrt{\left}=0.67\pm 0.11$ fm. Moreover, one find that extracting mass radius from the near-threshold differential cross-section of heavy quarkoniums is always affected by large $|t|_{min}$. These obtained results may provide important theoretical reference for understanding of nucleon structure and future relevant experiments., Comment: 7pages, 10figures

The purpose of this paper is to investigate working performance for a four-stroke compressed air engine via numerical studies. A mathematical model is developed to study the influence of several operative parameters on working performance. The mathematical model consists of thermodynamic model, each stroke model and dynamic model. In addition, a working principle and an experimental system of the compressed air engine are set up. The aims are: to introduce the novel four-stroke engine and to quantify the influence of rotational speed, supply pressure and supply temperature on working characteristics. The simulation and analysis show several meaningful results. The compressed air engine has higher cylinder pressure and work efficiency in lower speed stage, and the increase of the supply pressure can effectively improve indicated work and work efficiency. However, supply temperature has little effect on the performance of the compressed air engine. Therefore, the study of this work will provide a certain guidance function for further study on optimizing design of the compressed air engine.

In this study, we prepared Na-doped Cu2ZnSn(S,Se)4 [noted as (Na0.1Cu0.9)2ZnSn(S,Se)4] films on the Mo substrate using a simple and cheap sol–gel method together with the post-annealing technique. The effects of selenization temperature on the properties of Na-doped Cu2ZnSn(S,Se)4 were surveyed. The results indicated that some sulfur atoms in the films were substituted by selenium atoms by increasing the selenization temperature, and all films selenized at different temperatures had a kesterite structure. As the selenization temperature increased from 520 to 560 °C, the band gaps of the film can be tuned from 1.03 to 1 eV. The film with better morphology and opto-electrical properties can be obtained at an intermediate selenization temperature range (e.g., 540 °C), which had the lowest resistivity of 47.7 Ω cm, Hall mobility of 4.63 × 10−1 cm2/Vs, and carrier concentration of 2.93 × 1017 cm−3. Finally, the best power conversion efficiency (PCE) of 4.82% was achieved with an open circuit voltage (Voc) of 338 mV, a short circuit current density (Jsc) of 27.16 mA/cm2 and a fill factor (FF) of 52.59% when the selenization temperature was 540 °C.

This study presents a theoretical model and an experimental investigation of a piston engine driven by compressed air. The compressed air engine (CAE) is proposed which is modified from a conventio...

In order to realize the retrieval efficiency and detection precision of digital library collection resources, a new clustering algorithm (Fast density peak clustering,FDPC) based on fast texture density peak is proposed. Firstly, a framework of document image retrieval based on content description is given, based on median filter and direct-square equalization strategy, denoising and background processing of input document image are introduced, then density peak clustering (DPC) is used to classify image, and the convergence performance of DPC algorithm is improved by using dynamic truncation distance mode. Finally, based on the library standard test library (Corel), the performance of the proposed algorithm is validated experimentally, and the experimental results show that the proposed method has higher retrieval efficiency and retrieval accuracy.

Chicken infectious anemia virus (CIAV) is an immunosuppressive disease that causes enormous economic loss to the poultry industry worldwide, transmitted vertically and horizontally. In recent years, CIAV outbreaks have frequently occurred in southern China since 2014, especially in the Guangdong province. However, there is a lack of epidemiological studies of CIAV in Guangdong province. We performed PCR by using the serum and tissue samples collected from seven cities of Guangdong province. The PCR-positive tissue samples were inoculated into SPF eggs and MSB1 cells for virus isolation by blind-passages three times. This study isolated and characterized 325 serum samples and four tissue samples, the total positive CIAV rate of 62.15% in serum samples, and all four tissues were positive for the CIAV. However, the virus could only be isolated from MSB1 cells. Sequence analysis revealed that the four isolated comparisons with those in the GenBank showed high nucleotide similarities and were near clade C2. Our data showed over 60% of positive cases for CIAV serological analysis consist of seven cities, Which may lead to severe immunosuppressive effects in chickens. In summary, these findings provide new insights to guide molecular epidemiological surveillance of CIAV in Guangdong province.

Thermal management of power lithium-ion battery modules is very important to avoid thermal problems such as overheating and out of control, the study of thermal behavior of battery modules can provide guidance for the design and optimization of modules and thermal management. In this paper, a 3d thermal model of the power lithium-ion battery module is established based on STARCCM+ by using computational fluid dynamics (CFD) method, and a grid independence simulation test is used to determine the number of grids, the temperature distribution is analyzed under the condition of 1C charge current. The research results show that the internal temperature rises gradually with the charge going on, the temperature distribution of the cells is basically symmetrical. When the heat transfer coefficient is 5W/(m2⋅K) and the natural convective air inlet temperature is 300K, the module temperature uniformity is good. But because of the maximum temperature slightly higher than the temperature of thermal runaway, additional cooling methods need to be considered to cool the battery.

An effective battery thermal management system (BTMS) is crucial to ensure the battery temperature in an appropriate range and prolong the battery life. In this paper, a liquid cooling thermal management method for a li-ion battery module which is consisting of 12 prismatic batteries is set up, three circuitous channels embedded with a cooling plate are studied. Meanwhile, the performance evaluations of the battery module by considering different cooling conditions and battery arrangement are investigated numerically. The effects of the flow area of cooling plate and mass flow rate of coolant on the peak temperature and temperature difference of the battery module during charge/discharge process are examined. The larger flow area is experienced with a lower maximum temperature. Increases of maximum temperature and temperature difference are shown at lower mass flow rate. This paper provides guidance for the design and optimization of the module and thermal management.

Cation substitution is a promising approach to reduce the antisite defects and further improve the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) cells. In this paper, silver (Ag) has been introduced into Cu2ZnSn(S,Se)4 (CZTSSe) thin film to replace Cu partially and form (Cu1-xAgx)2ZnSn(S,Se)4 (0 &le, x &le, 1) (CAZTSSe) alloy films by combination of solution method and a rapid annealing technique. The fundamental properties of the mixed Ag-Cu kesterite compound are systematically reported as a function of the Ag/(Ag+Cu) ratio. The results show that band gap of kesterite CAZTSSe is incessantly increased by adjusting the Ag doping content, indicating that the CAZTSSe alloy film is a potentially applicable bandgap grading absorption layers material to obtain higher CZTSSe device. Furthermore, CAZTSSe alloy films with better electrical performance were also obtained by adjusting the Ag content during film fabrication. Finally, we also observed an increment in open circuit voltage (Voc) by 160 mV and an accompanying rise in device efficiency from 4.24 to 5.95%. The improvement is correlated to the improved grain size and decreased antisite defects of Cu instead of Zn site (CuZn) in the lattice. The Voc enhancement evidences that the solution method is facile and viable to achieve proper cation substitution toward higher efficiency kesterite solar cells. In addition, the CAZTSSe cell also displays better charge collection performance because of the higher fill factor (FF) and power conversion efficiency (PCE). Therefore, it can be concluded that the doping of Ag is a potentially appropriate method to reduce the Cuzn antisite defects of CZTSSe and improve efficiency of CZTSSe device.

In order to reduce exergy loss and optimize exergy efficiency of a compressed air engine (CAE), a theoretical exergy analysis model of the CAE is proposed and a working principle of the CAE based on a conventional IC engine is described. In addition, exergy balance equations of the working process at different stages are setup. The effects of rotational speed, supply pressure and ambient temperature are revealed in the simulation analysis, which have important influences on the exergy efficiency of the CAE. All these analyses of this paper will provide a theoretical basis for further study on optimizing design of the CAE.

Trajectories of charged particles in two-dimensional axisymmetric magnetic fields bear obvious resemblance to epicyclods. The main focus of this study is the systematic assessment of the accuracy of the epicycloid approximation for particle trajectories under such conditions. We primarily discuss particle motion constrained to the equatorial plane of a magnetic dipole. It is shown that with well chosen epicycloid parameters, this approximation can remain accurate for conditions well outside the area of expected validity of the Guiding Center approach. Calculating the epicycloid parameters using exact results for particle motion in the equatorial plane of a magnetic dipole allows to retain the accuracy of this approximation to surprisingly high particle energies. We also show that this approach allows us to approximate the trajectory of a charged particle more accurately than its velocity.

Cation substitution is a promising approach to reduce the antisite defects and further improve the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) cells. In this paper, silver (Ag) has been introduced into Cu2ZnSn(S,Se)4 (CZTSSe) thin film to replace Cu partially and form (Cu1-xAgx)2ZnSn(S,Se)4 (0 ≤ x ≤ 1) (CAZTSSe) alloy films by combination of solution method and a rapid annealing technique. The fundamental properties of the mixed Ag-Cu kesterite compound are systematically reported as a function of the Ag/(Ag+Cu) ratio. The results show that band gap of kesterite CAZTSSe is incessantly increased by adjusting the Ag doping content, indicating that the CAZTSSe alloy film is a potentially applicable bandgap grading absorption layers material to obtain higher CZTSSe device. Furthermore, CAZTSSe alloy films with better electrical performance were also obtained by adjusting the Ag content during film fabrication. Finally, we also observed an increment in open circuit voltage (Voc) by 160 mV and an accompanying rise in device efficiency from 4.24 to 5.95%. The improvement is correlated to the improved grain size and decreased antisite defects of Cu instead of Zn site (CuZn) in the lattice. The Voc enhancement evidences that the solution method is facile and viable to achieve proper cation substitution toward higher efficiency kesterite solar cells. In addition, the CAZTSSe cell also displays better charge collection performance because of the higher fill factor (FF) and power conversion efficiency (PCE). Therefore, it can be concluded that the doping of Ag is a potentially appropriate method to reduce the Cuzn antisite defects of CZTSSe and improve efficiency of CZTSSe device.

This study presents a theoretical model and an experimental investigation of a piston four-stroke engine driven by compressed air. The experiments in this study have used a test bench to examine the output torque and power performance of compressed air engine(CAE) at different working conditions. In addition, good agreement of simulation results is obtained between the model and the test. The results show that, as supply pressure increases, the output torque and power increase. The output torque and the power are maximized when the intake advance angle is - 70° CA, and the increase of the intake sustain angle will result in the increase of the torque and power. Consequently, this study of this paper will provide a theoretical and an experimental basis for further study on optimizing design of CAE.

A spiral bevel gear system supported on thrust bearings considering the coupled bending-torsional nonlinear vibration is proposed and an eight degrees of freedom (8DOF) lumped parameter dynamic model of the spiral bevel gear system combined with time-varying stiffness, static transmission error, gear backlash, and bearing clearances is investigated. The spiral bevel gear system is analyzed with the equations of motion and the dynamic response is solved using the Runge-Kutta method. The effects of mesh frequency, mesh damping coefficient, load coefficient, and gear backlash are revealed, which describe the true mesh characteristics of the spiral bevel gear system. The bifurcation characteristics as jump discontinuities, periodic windows, and chaos are obtained by studying time histories, phase plane portraits, Poincaré maps, Fourier spectra, and global bifurcation diagrams of the gear system. The results presented in this study provide some useful information for engineers in designing and controlling such gear systems.

The purpose of this paper is to investigate working performance for a four-stroke piston type compressed air engine (CAE) via experimental research. A conventional internal combustion engine(IC engine) is modified to a four-stroke CAE and a mathematical model is set up. Working performances are investigated by output torque, power, air consumption, exhaust pressure, exhaust temperature and cylinder pressure on a test bench. The CAE is installed on a vehicle for the road test. The experiment and analysis show several meaningful results. The increase of the supply pressure will result in the increase of the rotational speed, and it can effectively improve the output torque and power. However, it can lead to an increase in air consumption. The success of this application demonstrates compressed air cars are likely to be industrialized duo to their zero pollution and zero emissions.

To increase software productivity and enhance its quality, techniques for software reuse have attracted more and more attention in recent years. Among these techniques, application generator is a rather practical one but without deep explorations yet. In this paper, at first we examine the application generator in terms of characteristics of software reuse. And then, as a case study of application generator technique, the development of JR-DSSG and its features are presented. Finally, we end this paper with a discussion of intended further work.

Traditional AI systems are brittle in the sense that they fail miserably when presented with problems even slightly outside of their limited range of expertise. A powerful, extensible strategy of Distributed Artificial Intelligence (DAI) for overcoming such bounds is to put the system in a society of systems. So the ability to coordinate group activities of individuals and to communicate between each other is necessary for a language describing DAI systems. Agent-oriented language NUML is such a language. It is a specific kind of object-oriented language. To give formal semantics to NUML, there is the problem to formalise object-oriented programming paradigm which is still open. The theory of higher-order π-calculus is a concurrent computation model with sufficient capability, which provides us a mathematical tool to do the formalization. This paper tries to use higher-order π-calculus to formalise NUML.

A failure-detection scheduler for an online production system must strike a tradeoff between performance and reliability. If failure-detection processes are run too frequently, valuable system resources are spent checking and rechecking for failures. However, if failure-detection processes are run too rarely, a failure can remain undetected for a long time. In both cases, system performability suffers. We present a model-based learning approach that estimates the failure rate and then performs an optimization to find the tradeoff that maximizes system performability. We show that our approach is not only theoretically sound but practically effective, and we demonstrate its use in an implemented automated deadlock-detection system for Java.

Deadlock occurrences represent not only abnormal states but also fatal errors, thus it is natural to consider deadlock occurrences as runtime exceptions. Exception handlers can be exploited to resolve potential deadlock occurrences during the execution of code that is not deadlock free and that can be unchangeable, invisible, or dynamically loaded from networks. This paper describes an approach of deadlock resolution via exceptions with an emphasis on the design, application and implementation of deadlock exceptions and their handlers, and shows that the approach is practical and effective in incorporating code that is not deadlock free into dependable Java applications.