We propose test statistics based on the penalized spline to decide between generalized linear models and generalized partially linear models. The numerical performance of the proposed statistics is ...comparable to that of their kernel-based competitors, which have been shown to be asymptotically normal in the literature (Härdle et al. in J Am Stat Assoc 93:1461–1474, 1998). We also numerically explore the possibility of using the proposed statistics for goodness of fit checking for GLM. The proposed proposed procedures are illustrated to analyze two datasets.
We propose a residual-marked empirical process test to check goodness of fit for generalized partially linear models. The proposed test can gain dimension reduction, is shown to be consistent, and ...can detect root-
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local alternatives. We further establish asymptotic distributions of the proposed test under the null hypothesis and analyze asymptotic properties under the local and global alternatives, and suggest a bootstrap procedure for calculating the critical value. We investigate its numerical performance by simulation experiments and illustrate its utilization in two real data examples.
The need to improve the protection capability of spacecraft shield structure is urgent, owing to the deterioration of space environment caused by orbital debris. Reactive material is a kind of ...impact-induced energetic composites, and using reactive material to protect spacecraft against hypervelocity impact of orbital debris is a new way. In this paper, the dynamic compression experiments of PTFE (polytetrafluoroethylene)/Al (aluminum) and PTFE (polytetrafluoroethylene)/Ti (titanium) reactive materials were carried out. The mechanical properties and impact-induced reaction characteristics of PTFE/Al and PTFE/Ti were compared. The experiments of projectiles with hypervelocity impact on Whipple shields with PTFE/Al, PTFE/Ti and Al2024 as bumper respectively were carried out by using two-stage light-gas gun, and the protective capability of these two reactive materials against hypervelocity impact are compared. The experimental results show that the protective capability of PTFE/Al and PTFE/Ti reactive materials is better than that of Al2024, and the protective capability of PTFE/Al reactive material is better than that of PTFE/Ti. Through theoretical calculation and numerical simulation, the reasons for the difference of protective capability of different reactive materials are analyzed, and the ballistic limit curves of Whipple shield structures are compared.
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•Through hypervelocity impact experiments，the resistances of reactive materials to hypervelocity impact were compared.•The reasons of different resistance to hypervelocity impact are analyzed by theoretical calculation.•The ballistic limit curves of reactive material Whipple shields and Al2024 Whipple shield are compared.
•Expansion processes of debris clouds are obtained in experiments.•A new debris cloud model for reactive material bumper is presented.•Reactive material bumper can make debris cloud expand ...faster.•Reactive material bumper can decelerate projectile fragments.•Reactive material bumper can reduce load of impact of debris cloud on rear wall.
In this paper, a debris cloud model is presented for the case of hypervelocity impact of the spherical projectile on the thin PTFE (polytetrafluoroethylene)/Al (aluminum) reactive material bumper at normal incidence. The experiments of projectiles with hypervelocity impact on Whipple shields with PTFE/Al and Al2024 as bumper respectively were carried out by using two-stage light-gas gun, and the movement process of debris cloud was recorded through laser shadow photography system. According to the numerical simulation results and the laser shadow photographs of debris cloud obtained from the experiment of hypervelocity impact, two parts named as internal and external debris cloud are considered in the theoretical model. Several assumptions are made, and the theoretical model of debris cloud is developed by the conservation laws of mass, momentum and energy. Four characteristic velocities of the debris cloud are first calculated, and thus the whole evolution process of the debris cloud is plotted according to those velocities. By comparing the size of the debris cloud shown in the experiment, it can be concluded that the theoretical model agrees well with the experimental results. Moreover, the characteristic velocities of projectile fragments and bumper fragments in the debris cloud are calculated, and the mass areal density and momentum areal density distribution of the debris cloud on the rear wall are also obtained. Additionally, the effects of the detonation reaction of the reactive material bumper on the projectile during the impact are analyzed in contrast with the results on the Al2024 bumper. It is indicated that the detonation reaction of PTFE/Al can reduce the velocity of center of mass of debris cloud and increase the expansion velocity of debris cloud. PTFE/Al bumper can reduce damage caused by debris cloud to rear wall.
This paper reports on experiments involving deep underwater explosion (UNDEX) that were conducted in a pressure container. The bubble pulsation behavior due to the deep UNDEX is recorded by a ...high-speed camera for equivalent depths up to 350 m. The bubble images show that although the shape of the explosive package affects the bubble shape at the initial moment, the bubble easily becomes spherical in shallow water which is 0.8m and 100m depth, but never becomes spherical during the whole first pulsation in deep water which is 200m, 300m and 350m in this paper. Solutions of the Rayleigh–Plesset equation fit well with the experimental data, and the value of the polytropic index γ of the gaseous detonation products changes from 1.25 to 1.3 as the depth is increased. Finally, empirical laws governing the pulsation of a deep-UNDEX bubble are established. The experimental pulsation period and that from the Rayleigh–Plesset equation agree with that obtained empirically, but the maximum radius is smaller than the empirical one. This phenomenon shows that the water depth not only creates a high hydrostatic pressure for the bubble but also changes the energy-release process of a deep UNDEX.
In this study, concrete was selected to investigate the real-time splitting tensile mechanical and fracture behaviours of brittle materials using the Brazilian test under concentrated and distributed ...boundary conditions. The digital image correlation (DIC) method was adopted to evaluate the tensile strength and failure process in Brazilian tests using a high-resolution camera. The DIC results showed that the position of the crack initiation randomly occurred at the centre of a disc and at the boundary in Brazilian tests with concentrated loads (BTC). Comparatively, the crack initiated at the centre of discs in most Brazilian tests with distributed loads (BTD), as validated by the DIC results. Our results indicated that the average nominal tensile strength of specimens cracking at the boundary was larger than that of specimens cracking at the centre in the BTC, suggesting that the nominal tensile strength measured by the Brazilian test was related to the failure process of the discs. Moreover, this study demonstrated that the tensile strength measured by the Brazilian test was dependent on the boundary conditions. The equation recommended by the ISRM (International Society for Rock Mechanics) might slightly overestimate the tensile strength of brittle materials based on the pure elastic theory and hyperbolic-distributed loading conditions at the boundaries.
The proliferation of blockchain technology has resulted in diverse token standards, posing challenges for compatibility, security, and performance in existing cross-chain bridges. This paper ...introduces a novel framework capable of concurrently facilitating fungible token exchange, as well as the processing of both individual and batch non-fungible tokens (NFTs). We deploy token bridges that meet different token standards to support cross-chain staking and unlocking of ERC20, ERC721, and ERC1155. To minimize both waiting times and handling fees, we relocate processes necessitating frequent transactions and verifications to the sidechain. Additionally, we adopt a batch-processing approach for tokens necessitating cross-chain transfers, leveraging payment channels to facilitate efficiency. The system’s reliability is upheld through the validator group. Validators acquire an initial reputation value by making deposits and enhance both their rewards and reputation by successfully completing NFT auction tasks on the sidechain. We use OpenZeppelin’s security library functions to standardize token operations, and carefully design the validator’s reward, punishment, and reputation mechanisms. Our comprehensive contract security audit and system analysis validate our solution’s effectiveness in mitigating common vulnerabilities and internal threats. Implementation and testing with Ethereum and its test network demonstrate substantial reductions in transmission time for key cross-chain token steps by nearly half. Moreover, our framework showcases efficiency and cost-effectiveness with an average gas cost of 693,379.
The excitation and speed control of marine diesel engine plays an important role in the stability of marine power station system. In order to verify the feasibility of a new type of controller used ...in the marine power station system, it is necessary to understand the working characteristics of the diesel generator set in the condition of switching and grid connection power generation. The paper firstly researched and established the nonlinear mathematical model of ship power system, and then based on the Hamilton energy theory, designed the nonlinear excitation controller of diesel speed coordination unit, finally achieved the ship power station simulation system related to passivity based controller based on Simulink simulation platform. The simulation results show that the passivity based controller can keep the stability of the system in the process of no-load start-up, load sudden change and grid connection power generation and it has a certain value in engineering applications.
From the celebrated Gaussian mixture, model averaging estimators to the cutting-edge multi-Bernoulli mixture of various forms, finite mixture models offer a fundamental and flexible means to deal ...with uncertainties arisen in the estimation and learning realm. In the context of recursive estimation, both the uncertainties due to model maneuvering and multi-target data association derive a need for representing the single/multiple-target probability distribution by a finite mixture described by a number of parameters that are iteratively updated over time in the framework of Bayesian inference, which we call generally the Bayesian mixture (BM) filtering. In addition, density fusion between netted agents/sensors may be addressed by linearly combining their local estimations which are often correlated with each other in a complicated means, leading to a fused mixture too. In either case, the final estimate is given by the arithmetic average (AA) of all the weighted components in the mixture, regarding either a single target or multiple targets. Along with this are versatile mixture adaption and optimization strategies which aim to use a small number of components for the best fit to the target distribution. This survey provides a comprehensive overview of representative single/multiple-target BM filters and fusion approaches with the use of either a single sensor or multiple sensors in a unified and coherent fashion. State-of-the-art, relevant adaption and optimization technologies and remaining challenges are discussed. All strive to gain more insights of the approach.
•This is the first ever survey on Bayesian mixture (BM) filters and fusion approaches.•Versatile BM filters and fusion approaches are classified and analyzed on a unified base.•Motivation and important properties of the mixtures and optimization strategies are highlighted.•The state-of-the-art, remaining challenges and potential solutions are discussed.
•Giving the deformation mode of stiffened conical shell under deep water burst load.•Giving the trapezoidal deformation function for the deformation of the structure.•Giving the solution model of the ...maximum displacement of the structure.
The reinforced cylindrical and conical column structures are widely used structural forms in underwater vehicle structures. In this paper, the reinforced conical shell structure in the transition compartment of underwater vehicles was used as the research object. Based on the shock wave propagation theory and ABAQUS acoustic structure coupling numerical simulation method, the numerical simulation model of conical shell structure under deep-water explosion load was established.
The deep-water explosion simulation of conical shell structure under the conditions of different water depths, charges and explosion distances was carried out, and the deformation and failure mode of small depressions in the shell plate between ribs of stiffened conical shell structure was obtained, that was, independent small pits were formed along the axis direction. According to the theory of elastic-plastic deformation of plate and shell structure, the small pits of shell and plate between ribs were approximated as the deformation of trapezoidal plate, and the deformation function of trapezoidal plate was obtained by coordinate transformation. The deformation energy of plate and shell was divided into bending deformation energy and midplane strain energy. By establishing the correlation between explosion energy and deformation energy, the theoretical calculation model of the small pit deformation mode of shell and plate between ribs was obtained.
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