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Search Results: 1 - 10 of 36932 matches for " Jizhong Zhao "
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Effects of substituting rare-earth ion R by non-magnetic impurities in $R_2BaNiO_5$ - theory and numerical DMRG results
T. -K. Ng,Jizhong Lou,Zhao-Bin Su
Physics , 1999, DOI: 10.1103/PhysRevB.61.11487
Abstract: In this paper we study the effect of substituting R (rare-earth ion) by non-magnetic ions in the spin-1 chain material $R_2BaNiO_5$. Using a strong-coupling expansion and numerical density matrix renormalization group calculations, we show that spin-wave bound states are formed at the impurity site. Experimental consequences of the bound states are pointed out.
Task Assignment on Multi-Skill Oriented Spatial Crowdsourcing
Peng Cheng,Xiang Lian,Lei Chen,Jinsong Han,Jizhong Zhao
Computer Science , 2015,
Abstract: With the rapid development of mobile devices and crowdsourcing platforms, the spatial crowdsourcing has attracted much attention from the database community. Specifically, the spatial crowdsourcing refers to sending location-based requests to workers, based on their current positions. In this paper, we consider a spatial crowdsourcing scenario, in which each worker has a set of qualified skills, whereas each spatial task (e.g., repairing a house, decorating a room, and performing entertainment shows for a ceremony) is time-constrained, under the budget constraint, and required a set of skills. Under this scenario, we will study an important problem, namely multi-skill spatial crowdsourcing (MS-SC), which finds an optimal worker-and-task assignment strategy, such that skills between workers and tasks match with each other, and workers' benefits are maximized under the budget constraint. We prove that the MS-SC problem is NP-hard and intractable. Therefore, we propose three effective heuristic approaches, including greedy, g-divide-and-conquer and cost-model-based adaptive algorithms to get worker-and-task assignments. Through extensive experiments, we demonstrate the efficiency and effectiveness of our MS-SC processing approaches on both real and synthetic data sets.
Communicating Is Crowdsourcing: Wi-Fi Indoor Localization with CSI-based Speed Estimation
Zhiping Jiang,Jizhong Zhao,Xiang-Yang Li,Wei Xi,Kun Zhao,Shaojie Tang,Jinsong Han
Computer Science , 2013,
Abstract: Numerous indoor localization techniques have been proposed recently to meet the intensive demand for location based service, and Wi-Fi fingerprint-based approaches are the most popular and inexpensive solutions. Among them, one of the main trends is to incorporate the built-in sensors of smartphone and to exploit crowdsourcing potentials. However the noisy built-in sensors and multi-tasking limitation of underline OS often hinder the effectiveness of these schemes. In this work, we propose a passive crowdsourcing CSI-based indoor localization scheme, C2 IL. Our scheme C2 IL only requires the locating-device (e.g., a phone) to have a 802.11n wireless connection, and it does not rely on inertial sensors only existing in some smartphones. C2 IL is built upon our innovative method to accurately estimate the moving distance purely based on 802.11n Channel State Information (CSI). Our extensive evaluations show that the moving distance estimation error of our scheme is within 3% of the actual moving distance regardless of varying speeds and environment. Relying on the accurate moving distance estimation as constraints, we are able to construct a more accurate mapping between RSS fingerprints and location. To address the challenges of collecting fingerprints, a crowdsourcing- based scheme is designed to gradually establish the mapping and populate the fingerprints. In C2 IL, we design a trajectory clustering-based localization algorithm to provide precise real-time indoor localization and tracking. We developed and deployed a practical working system of C2 IL in a large office environment. Extensive evaluation results indicate that our scheme C2 IL provides accurate localization with error 2m at 80% at very complex indoor environment with minimal overhead.
Reliable Diversity-Based Spatial Crowdsourcing by Moving Workers
Peng Cheng,Xiang Lian,Zhao Chen,Rui Fu,Lei Chen,Jinsong Han,Jizhong Zhao
Computer Science , 2014,
Abstract: With the rapid development of mobile devices and the crowdsourcig platforms, the spatial crowdsourcing has attracted much attention from the database community, specifically, spatial crowdsourcing refers to sending a location-based request to workers according to their positions. In this paper, we consider an important spatial crowdsourcing problem, namely reliable diversity-based spatial crowdsourcing (RDB-SC), in which spatial tasks (such as taking videos/photos of a landmark or firework shows, and checking whether or not parking spaces are available) are time-constrained, and workers are moving towards some directions. Our RDB-SC problem is to assign workers to spatial tasks such that the completion reliability and the spatial/temporal diversities of spatial tasks are maximized. We prove that the RDB-SC problem is NP-hard and intractable. Thus, we propose three effective approximation approaches, including greedy, sampling, and divide-and-conquer algorithms. In order to improve the efficiency, we also design an effective cost-model-based index, which can dynamically maintain moving workers and spatial tasks with low cost, and efficiently facilitate the retrieval of RDB-SC answers. Through extensive experiments, we demonstrate the efficiency and effectiveness of our proposed approaches over both real and synthetic data sets.
Glucocorticosteroid-sensitive inflammatory eosinophilic pseudotumor of the bladder in an adolescent: a case report
Danfeng Xu, Yushan Liu, Yi Gao, Xuezhi Zhao, Chuangyu Qu, Changlin Mei, Jizhong Ren
Journal of Medical Case Reports , 2009, DOI: 10.1186/1752-1947-3-136
Abstract: We present the case of a biopsy-proven inflammatory eosinophilic pseudotumor of the bladder in a previously healthy 16-year-old male adolescent with 2-month history of frequent micturition and dysuria with no significant apparent causative factors. The tumor regressed after a 6-week course of glucocorticosteroids.To the best of our knowledge, our case is a rare case of inflammatory eosinophilic pseudotumor of the bladder treated with complete conservative management. Due to its glucocorticosteroid-sensitive nature, we postulate that this disease belongs to a subgroup of eosinophilic disorders.Inflammatory eosinophilic pseudotumor (IEPT) of the bladder is a rare, benign and proliferative lesion of the submucosal stroma [1]. The first pediatric inflammatory eosinophilic bladder tumor was reported in 1960 and since then it has usually been termed eosinophilic cystitis [2]. A few case reports have described IEPT of the bladder in both adults and children. IEPT of the bladder presents as a generalized inflammation of the bladder as well as a localized bladder mass [3]. Despite the benign inflammatory process, malignant-appearing histologic features of IEPT of the bladder can require radical tumor resection [2]. We present a case of biopsy-proven IEPT of the bladder in an adolescent, with tumor regression after administration of glucocorticosteroids.In September 2005, a previously healthy 16-year-old boy was admitted to a local hospital with 2-month history of frequent micturition and dysuria, but no apparent causative factors. The patient had no known history of drug allergies. Physical examination revealed a palpable suprapubic mass. Urine analysis showed no evidence of infection. An ultrasound examination revealed a bladder mass. Computed tomography (CT) of the abdomen and pelvis revealed a solid homogeneic mass involving the wall of the dome and two lateral walls of the urinary bladder; the average thickness of the bladder wall was 1.9 cm (Figure 1A). CT scan with thr
Design of Array Processor Systems
Xia Peisu,Fang Xinwo,Wang Yuxiang,Yan Kaiming,Zhang Tingjun,Liu Yulan,Zhao Chunying,Sun Jizhong
计算机科学技术学报 , 1987,
Abstract: A new type of high performance array processor system is presented in this paper.Unlikethe conventional host-peripheral array processor systems,this system is designed with afunctionally distributed approach.The design philosophy is described first.Then the hardwareorganizations of two concrete systems,namely:150-AP and GF-10/12,including thecommunication between processors are shown.Some attractive system performances for usersprograms are also given.
Midgap States in Antiferromagnetic Heisenberg Chains with A Staggered Field
Jizhong Lou,Changfeng Chen,Jize Zhao,Xiaoqun Wang,Tao Xiang,Zhaobin Su,Lu Yu
Physics , 2005, DOI: 10.1103/PhysRevLett.94.217207
Abstract: We study low-energy excitations in antiferromagnetic Heisenberg chains with a staggered field which splits the spectrum into a longitudinal and a transverse branch. Bound states are found to exist inside the field induced gap in both branches. They originate from the edge effects and are inherent to spin-chain materials. The sine-Gordon scaling $h_s^{2/3}|\log h_s|^{1/6}$ ($h_s$: the staggered field) provides an accurate description for the gap and midgap energies in the transverse branch for $S=1/2$ and the midgap energies in both branches for $S=3/2$ over a wide range of magnetic field; however, it can fit other low-energy excitations only at much lower field. Moreover, the integer-spin S=1 chain displays scaling behavior that does not fit this scaling law. These results reveal intriguing features of magnetic excitations in spin-chain materials that deserve further investigation.
Antiferromagnetic Heisenberg ladders in a staggered magnetic field
Jize Zhao,Xiaoqun Wang,Tao Xiang,Zhaobin Su,Lu Yu,Jizhong Lou,Changfeng Chen
Physics , 2005, DOI: 10.1103/PhysRevB.73.012411
Abstract: We study the low-energy excitations of the spin-1/2 antiferromagnetic Heisenberg chain and $N$-leg ($N$=2, 3, 4) ladders in a staggered magnetic field $h_s$. We show that $h_s$ induces gap and midgap states in all the cases and examine their field scaling behavior. A modified boundary scheme is devised to extract accurate bulk excitation behavior. The gap values converge rapidly as $N$ increases, leading to a field scaling exponent $\gamma=1/2$ for both the longitudinal and transverse gaps of the square lattice ($N \to \infty$). The midgap states induced by the boundary edge effects share the bulk gap scaling exponents but their overall scaling behavior in the large-N limit needs further investigation.
Correlation effects for semiconducting single wall carbon nanotube: a density matrix renormalization group study
Fei Ye,Bing-Shen Wang,JiZhong Lou,Zhao-Bin Su
Physics , 2005, DOI: 10.1103/PhysRevB.72.233409
Abstract: In this paper, we report the applicability of the density matrix renormalization group(DMRG) approach to the cylindrical single wall carbon nanotube (SWCN) for purpose of its correlation effect. By applying the DMRG approach to the $t$+$U$+$V$ model, with $t$ and $V$ being the hopping and Coulomb energies between the nearest neighboring sites, respectively, and $U$ the onsite Coulomb energy, we calculate the phase diagram for the SWCN with chiral numbers ($n_{1}=3, n_{2}=2$), which reflects the competition between the correlation energy $U$ and $V$. Within reasonable parameter ranges, we investigate possible correlated groundstates, the lowest excitations and the corresponding correlation functions in which the connection with the excitonic insulator is particularly addressed.
Rejecting the Attack: Source Authentication for Wi-Fi Management Frames using CSI Information
Zhiping Jiang,Jizhong Zhao,Xiang-Yang Li,JinSong Han,Wei Xi
Computer Science , 2012,
Abstract: Comparing to well protected data frames, Wi-Fi management frames (MFs) are extremely vulnerable to various attacks. Since MFs are transmitted without encryption, attackers can forge them easily. Such attacks can be detected in cooperative environment such as Wireless Intrusion Detection System (WIDS). However, in non-cooperative environment it is difficult for a single station to identify these spoofing attacks using Received Signal Strength (RSS)-based detection, due to the strong correlation of RSS to both the transmission power (Txpower) and the location of the sender. By exploiting some unique characteristics (i.e., rapid spatial decorrelation, independence of Txpower, and much richer dimensions) of the Channel State Information (CSI), a standard feature in 802.11n Specification, we design a prototype, called CSITE, to authenticate the Wi-Fi management frames by a single station without external support. Our design CSITE, built upon off-the-shelf hardware, achieves precise spoofing detection without collaboration and in-advance finger-print. Several novel techniques are designed to address the challenges caused by user mobility and channel dynamics. To verify the performances of our solution, we implement a prototype of our design and conduct extensive evaluations in various scenarios. Our test results show that our design significantly outperforms the RSS-based method in terms of accuracy, robustness, and efficiency: we observe about 8 times improvement by CSITE over RSS-based method on the falsely accepted attacking frames.
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