LoTAD: long-term traffic anomaly detection based on crowdsourced bus trajectory data

As the development of crowdsourcing technique, acquiring amounts of data in urban cities becomes possible and reliable, which makes it possible to mine useful and significant information from data. Traffic anomaly detection is to find the traffic patterns which are not expected and it can be used to explore traffic problems accurately and efficiently. In this paper, we propose LoTAD to explore anomalous regions with long-term poor traffic situations. Specifically, we process crowdsourced bus data into TS-segments (Temporal and Spatial segments) to model the traffic condition. Later, we explore anomalous TS-segments in each bus line by calculating their AI (Anomaly Index). Then, we combine anomalous TS-segments detected in different lines to mine anomalous regions. The information of anomalous regions provides suggestions for future traffic planning. We conduct experiments with real crowdsourced bus trajectory datasets of October in 2014 and March in 2015 in Hangzhou. We analyze the varieties of the results and explain how they are consistent with the real urban traffic planning or social events happened between the time interval of the two datasets. At last we do a contrast experiment with the most ten congested roads in Hangzhou, which verifies the effectiveness of LoTAD.     

\mathcal{MD}-HBase: design and implementation of an elastic data infrastructure for cloud-scale location services

The ubiquity of location enabled devices has resulted in a wide proliferation of location based applications and services. To handle the growing scale, database management systems driving such location based services (LBS) must cope with high insert rates for location updates of millions of devices, while supporting efficient real-time analysis on latest location. Traditional DBMSs, equipped with multi-dimensional index structures, can efficiently handle spatio-temporal data. However, popular open-source relational database systems are overwhelmed by the high insertion rates, real-time querying requirements, and terabytes of data that these systems must handle. On the other hand, key-value stores can effectively support large scale operation, but do not natively provide multi-attribute accesses needed to support the rich querying functionality essential for the LBSs. We present the design and implementation of $\mathcal {MD}$ -HBase, a scalable data management infrastructure for LBSs that bridges this gap between scale and functionality. Our approach leverages a multi-dimensional index structure layered over a key-value store. The underlying key-value store allows the system to sustain high insert throughput and large data volumes, while ensuring fault-tolerance, and high availability. On the other hand, the index layer allows efficient multi-dimensional query processing. Our optimized query processing technique accesses only the index and storage level entries that intersect with the query region, thus ensuring efficient query processing. We present the design of $\mathcal {MD}$ -HBase that demonstrates how two standard index structures—the K-d tree and the Quad tree—can be layered over a range partitioned key-value store to provide scalable multi-dimensional data infrastructure. Our prototype implementation using HBase, a standard open-source key-value store, can handle hundreds of thousands of inserts per second using a modest 16 node cluster, while efficiently processing multi-dimensional range queries and nearest neighbor queries in real-time with response times as low as few hundreds of milliseconds.     

Passive single chip wireless microwave pressure sensor

A novel micromachined passive wireless pressure sensor is presented. The device consists of a tuned circuit operating at 10 GHz fabricated on to a SiO₂ membrane, supported on a silicon wafer. A pressure difference across the membrane causes it to deflect so that an antenna circuit detunes. The circuit is remotely interrogated to read off the sensor data wirelessly. The chip area is 5 mm × 4 mm and the membrane area is 2 mm² with a thickness of 4 μm. Two on-chip passive resonant circuits were investigated: a meandered dipole and a zigzag antenna. Both have a physical length of 4.25 mm. The sensors show a shift in their resonant frequency in response to changing pressure of 10.28–10.27 GHz for the meandered dipole, and 9.61–9.58 GHz for the zigzag antenna. The sensitivities of the meandered dipole and zigzag sensors are 12.5 kHz/mbar and 16 kHz/mbar respectively.     

Cryptanalysis of a knapsack-based probabilistic encryption scheme

Wang et al. [B. Wang, Q. Wu, Y. Hu, A knapsack-based probabilistic encryption scheme, Information Sciences 177(19) (2007) 3981-3994] proposed a high density knapsack-based probabilistic encryption scheme with non-binary coefficients. In this paper, we present a heuristic attack that can be used to recover the private key parameters from the known public key parameters. In particular, we show that the restrictions imposed on the system parameters allow the attacker to recover a short list of candidates for the first half of the public key. The second half of the public key can then be recovered using an attack based on lattice basis reduction. Finally, by encrypting an arbitrary plaintext using the known public key then decrypting the resulting ciphertext using these estimated candidate solutions, the right private key can be uniquely determined.     

Four Voltmeter Vector Impedance Meter Based on Virtual Instrumentation

In this paper, a digital vector impedance half-bridge meter based on virtual instruments is designed, implemented and tested. Here, not only the accuracy of the magnitude of the impedance is considered but, more importantly, its phase measurement accuracy. The meter utilizes a four-voltmeter method which is a basic modification of the well-known three-voltmeter method. The half-bridge is constructed with commercially available data acquisition (DAQ) board in the form of peripheral control interconnect cards incorporated in personal computers. The DAQ board is used only to acquire the voltages instead of using four separate voltmeters, while the excitation signal is produced by an integrated circuit signal generator. The main error in this method arises from the error in measuring the voltage values. Since the resolution of the DAQ board used here is 16 bits; expect that absolute errors due to A/D conversion will be around 0.305 mV for ±10 V range. Detailed error analysis of the method is included in the context of the paper. It is found that the errors in the impedance magnitude is fairly small and relatively less sensitive on the resolution of the voltmeters because of the relative measurements in the half bridge with a precise reference resistance. The original three voltmeter vector impedance meter has relatively large error in the phase especially in the small phase angles. To decrease the phase error to an acceptable range, one has to increase the resolution of the voltmeter appreciably, which makes them expensive. The other solution to reduce the error in the phase angle with less cost is to add a fourth voltmeter which acquires directly the small phase angles. In this case, it is found that, a much lower resolution voltmeter can be utilized while achieving an acceptable measurement accuracy of the impedance.     

Speciation, selective extraction and preconcentration of chromium ions via alumina-functionalized-isatin-thiosemicarbazone

A method is presented and described for speciation, extraction and preconcentration of Cr(III) and Cr(VI) based on dynamic and static solid phase extraction techniques. Three newly designed alumina phases-physically adsorbed-isatin-thiosemicarbazone (I-III) were synthesized, characterized, tested for stability and applied as inorganic ion exchangers and chelating solid sorbents for various metal ions. The selectivity characteristics incorporated into these alumina phases were studied and evaluated via determination of the distribution coefficients and separation factors of chromium species versus other interacting metal ions. Quantitative recovery of Cr(VI) was accomplished by alumina phases (I-III) in pH 1.0 giving percentage extraction values of approximately 99.9-100.0%, while Cr(III) was found to be quantitatively recovered by these sorbents in pH 7.0 leading to percentage extraction values approximately 100.0% with minimal or no interference between these two species under the studied buffering conditions. Selective solid phase speciation and preconcentration of Cr(III) and Cr(VI) in various real water samples were successfully performed and accomplished by newly designed alumina phases (I-III) via a preconcentration micro-column.     

Application of novel copolymer-TiO(2) membranes for some textile dyes adsorptive removal from aqueous solution and photocatalytic decolorization

Novel low density polyethylene-grafted-poly(4-vinylpyridine-co-acrylamide) (LDPE-g-P(4-VP/AAm)) films were prepared by means of gamma-radiation-induced graft copolymerization as support for photocatalytic application. Nanometer-sized TiO(2) particles were immobilized to the grafted LDPE via dip coating technique. The efficiency of immobilized photocatalyst is tested on two target pollutants (textile azo dyes: Remazol red RB-133 (RR RB 133) and reactive blue 2 (RB2)). The efficient photocatalytic ability as reflected in determined photobleaching rate of both dyes was observed and is comparable to that for the non-supported TiO(2) used in a typical slurry photoreactor. The LDPE-g-(4-VP/AAm) copolymers supported TiO(2) photocatalyst has the practical advantages of easy separation and removal from the polluted environment. It could be a viable technique for the safe disposal of textile wastewater into the water streams.     

On the performance of OFDM and single carrier communication over wideband HF channel: theory and practice

Telecommunication Systems - Using wideband High Frequency (WBHF) communication has not been a luxury now due to the urgent need for the transfer of large files over long distances without the need...     

An Advanced Apralog with Increased in vitro and in vivo Activity toward Gram-negative Pathogens and Reduced ex vivo Cochleotoxicity

We describe the convergent synthesis of a 5-O-β-D-ribofuranosyl-based apramycin derivative (apralog) that displays significantly improved antibacterial activity over the parent apramycin against wild-type ESKAPE pathogens. In addition, the new apralog retains excellent antibacterial activity in the presence of the only aminoglycoside modifying enzyme (AAC(3)-IV) acting on the parent, without incurring susceptibility to the APH(3’) mechanism that disables other 5-O-β-D-ribofuranosyl 2-deoxystreptamine type aminoglycosides by phosphorylation at the ribose 5-position. Consistent with this antibacterial activity, the new apralog has excellent 30 nM activity (IC₅₀) for the inhibition of protein synthesis by the bacterial ribosome in a cell-free translation assay, while retaining the excellent across-the-board selectivity of the parent for inhibition of bacterial over eukaryotic ribosomes. Overall, these characteristics translate into excellent in vivo efficacy against E. coli in a mouse thigh infection model and reduced ototoxicity vis à vis the parent in mouse cochlear explants.