Mobile crowdsensing (MCS) has heated up and has become a new paradigm of data collection. In the process of the task allocation of MCS, users are often required to provide their own location information with the server to conveniently dispatch some suitable tasks to them. However, it is possible for malicious servers to infer some sensitive information based on the user's location such as the user's home address or the user's trajectory and so on which will cause serious privacy issues. Recently, differential privacy (DP) has become a promising privacy protection scheme. However, the existing DP schemes in location privacy protection for MCS do not pay attention to the accuracy of task allocation as equally as the effects of privacy protection, which often results in the task allocation to be inaccurate and inefficient. In order to overcome the shortcoming, we propose a novel MCS task allocation scheme integrating the mapping accuracy of task-worker with the privacy-preserving effect on the user's location. Besides edge devices, its implementation system consists of a task allocation server and a third party, both of which are semitrusted, that is, both of them only know about the user's rough location information but cannot obtain the user's exact location. At first, to improve the response speed of MCS task requests and the location privacy protection of MCS users, our scheme can exploit more than one edge-computing node nearby a user to cooperatively participate in MCS task allocation by aggregating him/her and the near users into groups. Then, our scheme can further enhance the location privacy protection effect based on the Johnson–Lindenstrauss (JL) transformation, which can achieve accurate task allocation and hold the merits of DP. Finally, we verify the feasibility by some experiments based on two data sets. The performance is compared with that of $t$ he typical DP. The results show that our scheme not only provides strict privacy guarantees but also has higher performance.
Simulation of Micro Blanking Process of Square Hole with Fillet was carried out based on DEFORM-3D.The ratio of burnish depth, shear depth and fracture depth to sheet thickness under different relative blanking clearance (c/t) was analyzed.The results show that the burnish depth at the fillet increases generally with the increasing blanking clearance, while the burnish depth at the straight-line segment firstly increases and then decreases with the increasing blanking clearance.The relationship between burr height and relative blanking clearances (c/t) was discussed.Results show that the average burr height increases with the increasing blanking clearance.
The vulnerable sensitivity to laser linewidth induced inter-carrier interference (ICI) has long been recognized as a major problem to coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems. Among the existing phase noise compensation algorithms, the RF-pilot aided phase recovery (RAPR) method shows a better compensation capability to laser linewidth. However, RAPR may fail to extract the pre-inserted RF-pilot at the receiver due to the influence of carrier frequency offset (CFO). An effective frequency offset estimation (FOE) is thus required to implement before performing RAPR. In consideration of the fact that the conventional FOE algorithm not only has high computational complexity, but more importantly cannot work in coordination with RAPR, a new RF-pilot aided frequency offset estimation (RAFOE) algorithm is proposed, in which CFO can be easily estimated by searching the peak of spectral samples. Furthermore, in order to obtain the optimum compensation performance with lower computing cost at combining RAFOE and RAPR, a joint frequency offset and phase noise compensation scheme is also proposed, and its performance is numerically verified in a 475 Gbit/s polarization multiplexed 16-ary quadrature amplitude modulation coherent optical orthogonal frequency-division multiplexing (PM-16QAM- CO-OFDM) system.
A cloud server with high performance/cost, performance/Watt, high-density and high scalability has attracted more attentions from academy and industry field. How to efficiently share and aggregate resources (e.g., computing, storage, I/O bandwidth) is the design focus of cloud server. This paper proposed a 2 D-torus cloud server architecture bas e d on SDC (S oft ware Defined Cluster), in which CPU can share the network and storage resources on demand. In a cloud server, there are two communication types (i.e., local mode and remote mode). To meet these communication demands, this paper proposed a kind of two-level interconnection networks in which the first-level is corresponding to the local communication and the second-level is aiming at the remote communication. For local communication, an Ethernet switch and a Shared Storage Controller (SSC) were proposed to solve the problem. For remote transmission, this paper implements an Interconnection Fabric Controller (IFC) to support the remote data exchanging. The IFC focuses on resolving the router computing, port ar biter, link flow control, retransmission and high speed link transfer protocol. Furthermore, we demonstrate a cloud server with 4 ×4 CPUs based on FP GA. Results of simulation and experiments demonstrate that the above-mentioned designs are valid and feasible.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Numerical and experimental studies were conducted to uncover the physical aspects of a liquid jet injected into a supersonic crossflow with gas throttling systematically. The results were obtained with the inflow conditions of a Mach number of 2.0, a total temperature of 300 K, and a total pressure of 0.55 MPa. The results show that fuel–air mixing is considerably enhanced due to shock-induced flow distortion by adding gas throttling. The strength of downstream backpressure determines the distance of forward movement of the throttling shock wave train and the flowfield structure in the channel. When the mass flux of gas throttling is high, the influence of throttling gas spreads across the expansion section, resulting in significant flow separation in front of the liquid jet. It is found that the spray flashback phenomenon is similar to the flame flashback phenomenon that occurs in the supersonic combustion process under the action of a precombustion shock train. The wall counterrotating vortex pair and induced cavity streamwise vortices are enhanced with the increase of the flux of gas throttling. The relatively high-pressure environment generated by gas throttling promotes the atomization of droplets. As a result, the mixing enhancement mechanism of a liquid jet in a supersonic crossflow with gas throttling is mainly due to the combined effects of 1) the shock waves separating the side wall boundary layer and modifying the local flow state of air in the combustor, which lead to a dramatic increase in fuel–air mixing, and 2) the streamwise vorticity values as well as the residence time resulting from channel blockage elevating.
With the development of society and the progress of the times, residents have higher demand for living standards. As a livelihood industry, the power system is closely related to everyone's life, which puts forward higher requirements for the safe and stable operation of the power grid. As the maintenance of safe and stable operation of power system, transportation inspection plays an irreplaceable key role. The digital intelligent operation and maintenance mode and technology is the main direction of current development. In this paper, the application of 3D terrain simulation technology in intelligent transportation inspection is proposed. Through the simulation of line terrain, operators can intuitively and accurately find suspicious faults and eliminate them in time. It is hoped that it will help to improve the operation and maintenance level of power grid and contribute to the intelligent development of power grid.
In a multicast network, a circular-shift linear code can be induced from a scalar linear code such that equipped with a nontrivially constructed source encoding matrix, and the induced code qualifies to be a circular-shift linear solution at a certain rate. However, for such an induced solution, there was no explicit characterization of the corresponding decoding matrix at every receiver. In this letter, we formulate a general rule to construct a source encoding matrix and a corresponding decoding matrix at every receiver. By application of the general rule, we further design new instances of the encoding and the decoding matrices, which can be expressed in a systematic form and involve fewer binary operations.
Based on burst clone,a burst encoding mechanism based on preemption is proposed to reduce burst loss rate.In the source edge nodes,some information data bursts(DBs) are encoded and a redundant DB is produced by the parity check code.In the core nodes,an information DB can preempt a redundant DB to reduce the contention from redundant DBs.And the burst loss rate of the information DB is reduced.In the destination edge nodes,the loss information DB in the core nodes can be recovered by the redundant DB.The proposed burst encoding mechanism is low computational complexity and efficiently reduces burst loss rate.
Optical burst switching (OBS) is a promising paradigm for the next generation Internet. Data channel scheduling algorithm is one of the key issues in OBS networks. In this paper, an efficient composite data channel scheduling algorithm is proposed, this algorithm select LAUC or LAUC-VF to schedule the arriving burst according to the current information of the void interval of the data channel. The algorithm reduces scheduling time of data burst while minimizing the void interval of the data channel. Simulation results show that the scheduling time of the proposed algorithm is close to LAUC, and the performance of data burst loss probability is better than LAUC-VF.
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