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The downstream uniformity of the atmospheric-pressure plasma jet array is a key technical problem in regards to large-scale applications. This paper presents a 2-D array device of five jets arranged in four different shapes designed from the perspective of symmetry. Various schemes were tested to determine the effects of jet arrangement on the downstream uniformity of the array: the completely symmetrical array X, the completely asymmetrical array J, and semi-symmetrical arrays T and U. The interactions in the arrays were observed via optical imaging as well as electrical and spectroscopic characterizations. The results show that the downstream plume pattern markedly changes with the jet arrangement. Peripheral plumes suppress the internal plumes to varying extent under different jet arrangements. The emission intensity of the helium line at 706.5 nm was taken as a criterion to find that downstream uniformity under the arrangements J, T, U, and X gradually decreases as the jet arrangement grows increasingly symmetrical. The electric field simulation shows that different jet arrangements cause various degrees of inhomogeneous electric field distributions, which in turn affect the charge transferred into each plasma jet and the distributions of active particles resulting in downstream uniformity variations. The results presented here may provide a theoretical foundation for improving the downstream uniformity of the plasma jet arrays and achieving large-scale plasma jet sources.

This paper presents a formal approach to specify and verify object-oriented programs written in the 'programming to interfaces' paradigm. In this approach, besides the methods to be invoked by its clients, an interface also declares a set of abstract and polymorphic function/predicate symbols, together with a set of constraints about these symbols. The methods declared in this interface are specified using these abstract symbols. A class implementing this interface can give its own definitions to the abstract symbols, as long as all the constraints are satisfied. This class implements all the methods declared in the interface such that the method specification declared in the interface are satisfied w.r.t. the function symbol definitions in this class. Based on the constraints about the abstract symbols, client code using the interfaces can be specified and verified precisely without knowing what classes implement the interfaces. Given more information about the implementing classes, the specifications of the client code can be specialized into more precise ones without re-verifying the client code. [ABSTRACT FROM AUTHOR]

Abstract Background This systematic review with meta-analyses sought to answer whether casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) provided a remineralizing benefit superior to that of nonintervention or placebo. Methods Following Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, Cochrane databases, PubMed, EmBase, and Ovid up to May 20th, 2019, were scanned, only published in English. Study information extraction and methodological quality assessments were accomplished independently by two reviewers. The “Criteria for judging risk of bias in the ‘Risk of bias’ assessment tool” was used for methodological quality assessment. The continuous data was analyzed by mean difference (MD) or standardized mean difference (SMD) with a 95% confidence interval (CI). Review Manager 5.3 was used for statistical analysis. Outcome variables include quantitative light-induced fluorescence in clinical research, average surface roughness and surface microhardness in vitro. Results There were significant differences in the quantitative light-induced fluorescence (SMD = − 0.43, 95% CI: [− 0.79, − 0.07], P = 0.02), average surface roughness (SMD = − 8.21, 95% CI: [− 10.37, − 6.04], P

Gas spark closing switch is one of the most important components for a fast linear transformer driver (FLTD). In this paper, we describe the investigation of insulation gas media for a multi-gap multi-channel gas spark closing switch. A six-gap gas switch with corona needles was tested in a typical FLTD brick with two capacitors of 40 nF and a load resistor of about 10 Ω. Corona discharge current, self-breakdown voltage distribution, and triggered breakdown performance were tested when the gas switch was filled with air, N2, CO2, SF6/N2, and C4F7N/N2. When C4F7N/N2 was applied, there was no abnormal breakdown with low voltage found in the whole test process; the trigger breakdown delay time and switch jitter were very stable, and no pre-fire was found during about 2000 triggered shots. Therefore, we think the C4F7N/N2 gas mixture with a very little amount of C4F7N can dramatically improve the switch performance. It is valuable and easy to realize the application of C4F7N/N2 mixture in large scale pulsed power facilities.

Dealing with crosscutting concerns has been a critical problem in software development processes. To facilitate handling crosscutting concerns at design phases, we proposed an as-pect-oriented modeling and integration approach with UML activity diagrams. The primary concerns are depicted with UML activity diagrams as primary models, whereas crosscutting concerns are described with aspectual extended activity diagrams as aspect models. Aspect models can be integrated into primary models automatically. The AOM approach can reduce the complexity of design models. However, potential faults that violate desired properties of the software system might still be introduced during the modeling or integration processes. The verification technique is well-known for its ability to assure the correctness of models and uncover design problems before implementation. We propose a framework to verify aspect-oriented UML activity diagrams based on Petri net verification techniques. For verification purpose, we transform the integrated activity diagrams into Petri nets and prove the con-sistency of the transformation. Then, crosscutting concerns in system requirements are refined to properties in the form of CTL formulas. Finally, the Petri nets are verified against the formalized properties to report whether the aspect-oriented design models satisfies the requirements. Furthermore, we implement a tool named Jasmine-AOV to support the veri-fication process. Case studies are conducted to evaluate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

The existing techniques for reachability analysis of linear hybrid systems do not scale well to the problem size of practical interest. The performance of existing techniques is even worse for reachability analysis of a composition of several linear hybrid automata. In this paper, we present an efficient path-oriented approach to bounded reachability analysis of composed systems modeled by linear hybrid automata with synchronization events. It is suitable for analyzing systems with many components by selecting critical paths, while this task was quite insurmountable before because of the state explosion problem. This group of paths will be transformed to a group of linear constraints, which can be solved by a linear programming solver efficiently. This approach of symbolic execution of paths allows design engineers to check important paths, and accordingly increase the faith in the correctness of the system. This approach is implemented into a prototype tool Bounded reAchability CHecker (BACH). The experimental data show that both the path length and the number of participant automata in a system checked using BACH can scale up greatly to satisfy practical requirements. [ABSTRACT FROM AUTHOR]

In situ growth of TiO2 nanoparticles on reduced graphene oxide (RGO-TiO2) exhibits good performance of photocatalytic degradation under visible light. The photocatalytic efficiency of GO-TiO2 and RGO-TiO2 in degrading Methyl Orange could reach 99% and 96% within 2 h, respectively. The results showed that the optimum mass ratio of GO or RGO to TiO2 was 0.15. [ABSTRACT FROM AUTHOR]

As a critical component of a high-voltage direct current (HVDC) transmission system, resin impregnated paper (RIP) wall bushing has become a weak point because of its surface charge accumulation. This paper studies a model RIP wall bushing core designed by the equal capacitance method. The stationary resistive field along the gas−solid interface of the RIP wall bushing core is investigated theoretically by a gas model, which considers the non-linearly field-dependent volume conductivity. The results show that the gas conductivity along the core surface tends to be an arched distribution from the high-voltage conductor to the end shielding screen. The surface charge mainly accumulates at the turning point of the radius, which may threaten the core’s insulation. Then, the surface charge is obtained through a measurement system, where the experimental results are highly consistent with the simulation results. Considering the time constant of charge dissipation is nearly 15 min, it would be better to measure the surface charge on one axial direction of RIP wall bushing core after each voltage application. The simulation and experimental results of this paper can guide the design of a RIP wall bushing core.

Test case generation based on design specifications is an important part of testing processes. In this paper, Unified Modeling Language activity diagrams are used as design specifications. By setting up several test adequacy criteria with respect to activity diagrams, an automatic approach is presented to generate test cases for Java programs. Instead of directly deriving test cases from activity diagrams, this approach selects test cases from a set of randomly generated ones according to a given test adequacy criterion. In the approach, we first instrument a Java program under testing according to its activity diagram model, and randomly generate abundant test cases for the program. Then, by running the instrumented program we obtain the corresponding program execution traces. Finally, by matching these traces with the behavior of the activity diagram, a reduced set of test cases are selected according to the given test adequacy criterion. This approach can also be used to check the consistency between the program execution traces and the behavior of activity diagrams. [ABSTRACT FROM AUTHOR]

Titanium dioxide ceramic films have been prepared on titanium board by the micro-plasma oxidation method. The influence of reaction voltage (120, 140, 160, 180, and 200 V) on the structural and surface morphology of the film was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activity of the film was evaluated by the photodegradation of rhodamine B (Rh B). It was found that the films produced were microporous and consisted of crystalline titanium dioxide. The micropore size and the content of anatase and rutile TiO2 phase increased with the applied voltage. The relatively higher degradation efficiency for Rh B was obtained in the film produced in the voltage of 160 V. [Copyright &y& Elsevier]