A Review of Research on Privacy Protection of Internet of Vehicles Based on Blockchain

Numerous academic and industrial fields, such as healthcare, banking, and supply chain management, are rapidly adopting and relying on blockchain technology. It has also been suggested for application in the internet of vehicles (IoV) ecosystem as a way to improve service availability and reliability. Blockchain offers decentralized, distributed and tamper-proof solutions that bring innovation to data sharing and management, but do not themselves protect privacy and data confidentiality. Therefore, solutions using blockchain technology must take user privacy concerns into account. This article reviews the proposed solutions that use blockchain technology to provide different vehicle services while overcoming the privacy leakage problem which inherently exists in blockchain and vehicle services. We analyze the key features and attributes of prior schemes and identify their contributions to provide a comprehensive and critical overview. In addition, we highlight prospective future research topics and present research problems

Joint inversion of the magnetic anomaly due to a kimberlite pipe and its analytic signal

Diamonds and kimberlites -- Geophysical surveys for kimberlites -- Problem -- Main objectives -- Methodology -- Major concepts -- The progress of magnetic method and the historical development concerned of magnetic method survey for kimberlites -- Derivatives of the magnetic field -- Formulas of derivatives of the magnetic field -- Finite difference derivatives -- Comparison of the responses from two methods -- Inversion of the magnetic field -- Introduction of the magnetic field inversion -- The solutions -- Levenberg-marquardt method -- The convergence -- Tests for the magnetic inversion -- Inversion of the analytic signal -- Introduction of the analytic signal -- Forward modeling -- Method of inversion -- Tests -- Joint inversion of the magnetic field and its analytic signal -- Introduction of joint inversion -- The model of the joint inversion -- Forward modeling -- Fromulation of the joint inversion -- Normalization -- Weighting of the two sets of the data -- The convergence -- The technique of the joint inversion -- Application to the real data -- Conclusion and discussion

New metrics for prioritized interaction test suites

Combinatorial interaction testing has been well studied in recent years, and has been widely applied in practice. It generally aims at generating an effective test suite (an interaction test suite) in order to identify faults that are caused by parameter interactions. Due to some constraints in practical applications (e.g. limited testing resources), for example in combinatorial interaction regression testing, prioritized interaction test suites (called interaction test sequences) are often employed. Consequently, many strategies have been proposed to guide the interaction test suite prioritization. It is, therefore, important to be able to evaluate the different interaction test sequences that have been created by different strategies. A well-known metric is the Average Percentage of Combinatorial Coverage (shortly APCCλ), which assesses the rate of interaction coverage of a strength λ (level of interaction among parameters) covered by a given interaction test sequence S. However, APCCλ has two drawbacks: firstly, it has two requirements (that all test cases in S be executed, and that all possible λ-wise parameter value combinations be covered by S); and secondly, it can only use a single strength λ (rather than multiple strengths) to evaluate the interaction test sequence - which means that it is not a comprehensive evaluation. To overcome the first drawback, we propose an enhanced metric Normalized APCCλ (NAPCC) to replace the APCCλ Additionally, to overcome the second drawback, we propose three new metrics: the Average Percentage of Strengths Satisfied (APSS); the Average Percentage of Weighted Multiple Interaction Coverage (APWMIC); and the Normalized APWMIC (NAPWMIC). These metrics comprehensively assess a given interaction test sequence by considering different interaction coverage at different strengths. Empirical studies show that the proposed metrics can be used to distinguish different interaction test sequences, and hence can be used to compare different test prioritization strategies

Experimental research on the dynamic characteristics of gas-hybrid bearing-flexible rotor system

High-speed gas bearings for turbomachinery can dramatically improve the isentropic efficiency of turbine plants. Vibrations, especially low-frequency vibrations caused by the gas-film self-excited vibrations, significantly affect the safety and economy of the turbomachinery, which is dangerous at high rotational speeds. This experimental study focuses on the dynamic characteristics of a flexible rotor supported by gas hybrid bearing and driven by a radial turbine with high-pressure air. Cylindrical whirling, conical whirling, and first-order bending natural frequencies that change with bearing supply pressures were obtained by experimental modal analysis. Nonlinear mechanic behaviors, including gas film half-speed whirling and gas-film whip, in the experiments were identified by nonlinear measurements and analyses. The occurrence mechanism of gas-film whirling and whip is also discussed in this paper. Experiments for eliminating and restraining whirling and whip were conducted to investigate the gas bearing-rotor system stability effect of bearing supply pressure and elastic foundation. Some simple and effective measures were given to improve the stable rotational speed

Socio-Economic Aspects of Slum Dwellers in Karachi - A Case Study of 14 Slums in District Malir

Karachi is one of most populated cities in the world. Like every other most populated cities of developing world, slums are the major part of Karachi’s population contributing almost 50 percent of the city’s population. So, for the wellbeing and development of a city like Karachi, study of slums in the city and their wellbeing is of utmost importance. Slums in Karachi are widely spread throughout the city making it really difficult for the researchers to study the slum problems. This study is an exclusive attempt to study the socio-economic aspects of slum dwellers in Karachi. 14 slums from Malir district of Karachi were considered for this study as Malir district comprises of almost 15-20 percent of the total slums in Karachi. Major factors assumed and considered for finding socio-economic aspects of slum dwellers included gender, marital status, occupation, education level of household head, monthly income of household, household size and room occupancy and duration of their residence and status in a particular locality. At the end, policy recommendations were developed to improve the overall living conditions and socio-economic well being of the slum dwellers. Keywords: key words, orkforce sizing, job-shop production, holonic mode

Research on speed’s influence on hydrostatic bearing’s stiffness

Reynolds equation considering speed is solved using finite element method. Orifice hydrostatic gas bearing’s pressure distribution, load capacity and stiffness are obtained. Speed’s influenced on stiffness is studied. Experiment is conducted on turbine expander. Rotor operates under unbalance mass’s excitation. By analysis whipping frequency’s relation with the natural frequency of rotor-bearing system, stiffness can be calculated. The experiment result shows that bearing’s stiffness changes with rotor’s speed. When rotor’s speed is between 10000-50000 r/min, stiffness increased by 9.6 %. Because gas whirl only happens when rotor’s speed is above the first critical speed, the method has limited speed range

Experiment research on stability of herringbone grooved aerodynamic bearing-rotor system

Take experiment research on characteristics of turbine expansion engine’s shaft supported by herringbone grooved aerodynamic journal bearing, with the emphasis on its low frequency whirl. Get bearing’s taking-off speed and low frequency vibration characteristics by comprehensively analysis methods of spectrum diagram, haft orbit and time waveform and bifurcation diagram. The result shows that the graphite made herringbone groove hydrodynamic bearing can reach 37548 r/min and half-frequency vibration happens since 13021 r/min. With the speed up, rubbing exists and the amplitude of low frequency even bigger than power frequency. The result shows that the half-frequency is the main unstable factor