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Private Selection from Private Candidates [article]

Jingcheng Liu, Kunal Talwar
2018 arXiv   pre-print
Differentially Private algorithms often need to select the best amongst many candidate options. Classical works on this selection problem require that the candidates' goodness, measured as a real-valued score function, does not change by much when one person's data changes. In many applications such as hyperparameter optimization, this stability assumption is much too strong. In this work, we consider the selection problem under a much weaker stability assumption on the candidates, namely that
more » ... he score functions are differentially private. Under this assumption, we present algorithms that are near-optimal along the three relevant dimensions: privacy, utility and computational efficiency. Our result can be seen as a generalization of the exponential mechanism and its existing generalizations. We also develop an online version of our algorithm, that can be seen as a generalization of the sparse vector technique to this weaker stability assumption. We show how our results imply better algorithms for hyperparameter selection in differentially private machine learning, as well as for adaptive data analysis.
arXiv:1811.07971v1 fatcat:vkrlpuyml5g7zd2oyahhxceqoe

FPTAS for Counting Monotone CNF [article]

Jingcheng Liu, Pinyan Lu
2014 arXiv   pre-print
A monotone CNF formula is a Boolean formula in conjunctive normal form where each variable appears positively. We design a deterministic fully polynomial-time approximation scheme (FPTAS) for counting the number of satisfying assignments for a given monotone CNF formula when each variable appears in at most 5 clauses. Equivalently, this is also an FPTAS for counting set covers where each set contains at most 5 elements. If we allow variables to appear in a maximum of 6 clauses (or sets to
more » ... n 6 elements), it is NP-hard to approximate it. Thus, this gives a complete understanding of the approximability of counting for monotone CNF formulas. It is also an important step towards a complete characterization of the approximability for all bounded degree Boolean #CSP problems. In addition, we study the hypergraph matching problem, which arises naturally towards a complete classification of bounded degree Boolean #CSP problems, and show an FPTAS for counting 3D matchings of hypergraphs with maximum degree 4. Our main technique is correlation decay, a powerful tool to design deterministic FPTAS for counting problems defined by local constraints among a number of variables. All previous uses of this design technique fall into two categories: each constraint involves at most two variables, such as independent set, coloring, and spin systems in general; or each variable appears in at most two constraints, such as matching, edge cover, and holant problem in general. The CNF problems studied here have more complicated structures than these problems and require new design and proof techniques. As it turns out, the technique we developed for the CNF problem also works for the hypergraph matching problem. We believe that it may also find applications in other CSP or more general counting problems.
arXiv:1311.3728v2 fatcat:nvwgx5hqrrgfzpnsmltx3qrih4

Experimentally distinguishing electro-optic ef fects in silicon

Jingcheng Zhu Jingcheng Zhu, Zhanguo Chen Zhanguo Chen, Xiuhuan Liu Xiuhuan Liu, Jinbo Mu Jinbo Mu, Yanjun Gao Yanjun Gao, Wei Han Wei Han, Gang Jia Gang Jia
2012 Chinese Optics Letters (COL)  
Different electro-optic effects, such as Kerr effect, Pockels effect induced by the electric field or strain, and plasma dispersion effect exist in silicon. Experimentally distinguishing these effects is necessary for designing silicon-based electro-optic devices. According to their different polarization dependencies and frequency responses, these effects are measured and distinguished successfully via a transverse electro-optic modulation experiment based on the near-intrinsic silicon sample.
more » ... The results indicate that Pockels effect induced by the electric field or strain is primary among these effects in the near-intrinsic silicon sample.
doi:10.3788/col201210.082301 fatcat:ppt7uf53drfvlexcs3d7mibire

The Complexity of Ferromagnetic Two-spin Systems with External Fields [article]

Jingcheng Liu, Pinyan Lu, Chihao Zhang
2014 arXiv   pre-print
We study the approximability of computing the partition function for ferromagnetic two-state spin systems. The remarkable algorithm by Jerrum and Sinclair showed that there is a fully polynomial-time randomized approximation scheme (FPRAS) for the special ferromagnetic Ising model with any given uniform external field. Later, Goldberg and Jerrum proved that it is #BIS-hard for Ising model if we allow inconsistent external fields on different nodes. In contrast to these two results, we prove
more » ... for any ferromagnetic two-state spin systems except the Ising model, there exists a threshold for external fields beyond which the problem is #BIS-hard, even if the external field is uniform.
arXiv:1402.4346v1 fatcat:iqlhq5ejkjby7caic23lnljrry

The Perspective and Challenge of Nanomaterials in Oil and Gas Wastewater Treatment

Xiaoying Liu, Wenlin Ruan, Wei Wang, Xianming Zhang, Yunqi Liu, Jingcheng Liu
2021 Molecules  
Oil and gas wastewater refers to the waste stream produced in special production activities such as drilling and fracturing. This kind of wastewater has the following characteristics: high salinity, high chromaticity, toxic and harmful substances, poor biodegradability, and a difficulty to treat. Interestingly, nanomaterials show great potential in water treatment technology because of their small size, large surface area, and high surface energy. When nanotechnology is combined with membrane
more » ... eatment materials, nanofiber membranes with a controllable pore size and high porosity can be prepared, which provides more possibilities for oil–water separation. In this review, the important applications of nanomaterials in wastewater treatment, including membrane separation technology and photocatalysis technology, are summarized. Membrane separation technology is mainly manifested in ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). It also focuses on the application of semiconductor photocatalysis technology induced by TiO2 in the degradation of oil and gas wastewater. Finally, the development trends of nanomaterials in oil and gas wastewater treatment are prospected.
doi:10.3390/molecules26133945 pmid:34203335 fatcat:suixpzqp2zbzzi4zf36br6y72q

Achieving Accountability in Smart Grid

Jing Liu, Yang Xiao, Jingcheng Gao
2014 IEEE Systems Journal  
Smart grid is a promising power infrastructure that is integrated with communication and information technologies. Nevertheless, privacy and security concerns arise simultaneously. Failure to address these issues will hinder the modernization of the existing power system. After critically reviewing the current status of smart grid deployment and its key cyber security concerns, the authors argue that accountability mechanisms should be involved in smart grid designs. We design two separate
more » ... ntable communication protocols using the proposed architecture with certain reasonable assumptions under both home area network and neighborhood area network. Analysis and simulation results indicate that the design works well, and it may cause all power loads to become accountable. Index Terms-Accountability, advanced metering infrastructure (AMI), security, smart grid.
doi:10.1109/jsyst.2013.2260697 fatcat:am4yi4m3d5gdrbsakavmnwc35i

Decentralized Anonymous Micropayments [chapter]

Alessandro Chiesa, Matthew Green, Jingcheng Liu, Peihan Miao, Ian Miers, Pratyush Mishra
2017 Lecture Notes in Computer Science  
Micropayments (payments worth a few pennies) have numerous potential applications. A challenge in achieving them is that payment networks charge fees that are high compared to "micro" sums of money. Wheeler (1996) and Rivest (1997) proposed probabilistic payments as a technique to achieve micropayments: a merchant receives a macro-value payment with a given probability so that, in expectation, he receives a micro-value payment. Despite much research and trial deployment, micropayment schemes
more » ... e not seen adoption, partly because a trusted party is required to process payments and resolve disputes. The widespread adoption of decentralized currencies such as Bitcoin (2009) suggests that decentralized micropayment schemes are easier to deploy. Pass and Shelat (2015) proposed several micropayment schemes for Bitcoin, but their schemes provide no more privacy guarantees than Bitcoin itself, whose transactions are recorded in plaintext in a public ledger. We formulate and construct decentralized anonymous micropayment (DAM) schemes, which enable parties with access to a ledger to conduct offline probabilistic payments with one another, directly and privately. Our techniques extend those of Zerocash (2014) with a new privacy-preserving probabilistic payment protocol. One of the key ingredients of our construction is fractional message transfer (FMT), a primitive that enables probabilistic message transmission between two parties, and for which we give an efficient instantiation. Double spending in our setting cannot be prevented. Our second contribution is an economic analysis that bounds the additional utility gain of any cheating strategy, and applies to virtually any probabilistic payment scheme with offline validation. In our construction, this bound allows us to deter double spending by way of advance deposits that are revoked when cheating is detected.
doi:10.1007/978-3-319-56614-6_21 fatcat:yplgiwomajfhjl5zqvttmx34ou

Lumbar intraspinal microcystic/reticular schwannoma: Case report and literature review

Congcong Liu, Lianqi Yan, Qing Liu, Jing Li, Hongtao Jin, Jingcheng Wang, Youwen Deng
2018 Medicine  
Conceptualization: Jingcheng Wang, Youwen Deng. Data curation: Congcong Liu, Jing Li. Formal analysis: Qing Liu. Investigation: Lianqi Yan. Methodology: Congcong Liu, Hongtao Jin, Jingcheng Wang.  ...  Project administration: Jingcheng Wang. Resources: Qing Liu, Hongtao Jin. Software: Qing Liu. Supervision: Youwen Deng. Validation: Lianqi Yan. Visualization: Lianqi Yan, Jingcheng Wang.  ... 
doi:10.1097/md.0000000000012474 pmid:30278533 pmcid:PMC6181603 fatcat:ytodl53nijg2hjbg4zgxsttujy

FPTAS for Counting Weighted Edge Covers [chapter]

Jingcheng Liu, Pinyan Lu, Chihao Zhang
2014 Lecture Notes in Computer Science  
An edge cover of a graph is a set of edges in which each vertex has at least one of its incident edges. The problem of counting the number of edge covers is #P-complete and was shown to admit a fully polynomial-time approximation scheme (FPTAS) recently [10] . Counting weighted edge covers is the problem of computing the sum of the weights for all the edge covers, where the weight of each edge cover is defined to be the product of the edge weights of all the edges in the cover. The FPTAS in
more » ... cannot apply to general weighted counting for edge covers, which was stated as an open question there. Such weighted counting is generally interesting as for instance the weighted counting independent sets (vertex covers) problem has been exhaustively studied in both statistical physics and computer science. Weighted counting for edge cover is especially interesting as it is closely related to counting perfect matchings, which is a long-standing open question. In this paper, we obtain an FPTAS for counting general weighted edge covers, and thus solve an open question in [10] . Our algorithm also goes beyond that to certain generalization of edge cover. Preliminaries Dangling edge Following [10], we introduce dangling edges into our graph to simplify the description of our algorithm and proofs. Definition 2. A dangling edge e = (u, ) in a graph G(V, E) is such an edge with exactly one end point u ∈ V . A free edge e = ( , ) is an edge with no end points.
doi:10.1007/978-3-662-44777-2_54 fatcat:miz7g3jjfbam5b6vz6nyliz4le

Template-assisted syntheses of porous metal methylphosphonates

Zongbin Wu, Jingcheng Tian, Zhongmin Liu, Peng Tian, Lei Xu, Yue Yang, Yangyang Zhang, Xinhe Bao, Xiumei Liu, Xianchun Liu
2006 Journal of porous materials  
Neutral dibutyl methylphosphonate (DBMP) is used as a template to prepare porous metal methylphosphonates (metal = aluminum, titanium, zirconium). The removal of DBMP in the as-synthesized materials could be easily achieved by evaporation under vacuum without destroying the hybrid structure, as evidenced by elemental analyses, FT-IR spectra, 13 C CP/MAS NMR and nitrogen adsorptiondesorption isotherms. Thermal analyses show that three porous hybrid samples have high thermal stability in air. The
more » ... exothermic weight losses due to oxidation combustion of organic species occluded in samples appear after 730 K. Furthermore, the templating effect of DBMP is also confirmed by comparing the hybrid materials synthesized in the presence or the absence of the template.
doi:10.1007/s10934-006-5492-4 fatcat:wjnxdazrqjg5zdxljvby7xrrvq

Asynchronous Stochastic Proximal Optimization Algorithms with Variance Reduction [article]

Qi Meng, Wei Chen, Jingcheng Yu, Taifeng Wang, Zhi-Ming Ma, Tie-Yan Liu
2016 arXiv   pre-print
et al. 2013; , stochastic dual coordinate ascent (SDCA) (Tran et al. 2015) and randomized Kaczmarz algorithm (Liu, Wright, and Sridhar 2014) .  ...  Liu and Wright analyzed the asynchronous ProxSCD. They proved that the asynchronous ProxSCD can achieve near linear speedup if the delay is bounded by O(d 1 4 ), where d is the input dimension .  ... 
arXiv:1609.08435v1 fatcat:bq2jy5bhxjgcrkf5fzrm3f2a24

Principle Research on a Single Mass Piezoelectric Six-Degrees-of-Freedom Accelerometer

Jun Liu, Min Li, Lan Qin, Jingcheng Liu
2013 Sensors  
A signal mass piezoelectric six-degrees-of-freedom (six-DOF) accelerometer is put forward in response to the need for health monitoring of the dynamic vibration characteristics of high grade digitally controlled machine tools. The operating principle of the piezoelectric six-degrees-of-freedom accelerometer is analyzed, and its structure model is constructed. The numerical simulation model (finite element model) of the six axis accelerometer is established. Piezoelectric quartz is chosen for
more » ... acceleration sensing element and conversion element, and its static sensitivity, static coupling interference and dynamic natural frequency, dynamic cross coupling are analyzed by ANSYS software. Research results show that the piezoelectric six-DOF accelerometer has advantages of simple and rational structure, correct sensing principle and mathematic model, good linearity, high rigidity, and theoretical natural frequency is more than 25 kHz, no nonlinear cross coupling and no complex decoupling work.
doi:10.3390/s130810844 pmid:23959243 pmcid:PMC3812631 fatcat:7r53usuw4jhxzkv4wvsppdeyqe

Fault-Tolerant Privacy-Preserving Data Aggregation for Smart Grid

Huadong Liu, Tianlong Gu, Yining Liu, Jingcheng Song, Zhixin Zeng
2020 Wireless Communications and Mobile Computing  
Data Availability No data were used to support this study Yining Liu Guilin University of Electronic Technology, China.  ... 
doi:10.1155/2020/8810393 fatcat:heorx6sodrgt5fbvrbn5rwjccu

Joint Optimization of Control Strategy and Energy Consumption for Energy Harvesting WSAN

Zhuwei Wang, Zhicheng Liu, Lihan Liu, Chao Fang, Meng Li, Jingcheng Zhao
2022 Entropy  
With the rapid development of wireless sensor technology, recent progress in wireless sensor and actuator networks (WSANs) with energy harvesting provide the possibility for various real-time applications. Meanwhile, extensive research activities are carried out in the fields of efficient energy allocation and control strategy design. However, the joint design considering physical plant control, energy harvesting, and consumption is rarely concerned in existing works. In this paper, in order to
more » ... enhance system control stability and promote quality of service for the WSAN energy efficiency, a novel three-step joint optimization algorithm is proposed through control strategy and energy management analysis. First, the optimal sampling interval can be obtained based on energy harvesting, consumption, and remaining conditions. Then, the control gain for each sampling interval is derived by using a backward iteration. Finally, the optimal control strategy is determined as a linear function of the current plant states and previous control strategies. The application of UAV formation flight system demonstrates that better system performance and control stability can be achieved by the proposed joint optimization design for all poor, sufficient, and general energy harvesting scenarios.
doi:10.3390/e24050723 pmid:35626606 pmcid:PMC9142046 fatcat:p3brecsqv5av5p5fbexryv2cw4

Motion Sensitive Contrastive Learning for Self-supervised Video Representation [article]

Jingcheng Ni, Nan Zhou, Jie Qin, Qian Wu, Junqi Liu, Boxun Li, Di Huang
2022 arXiv   pre-print
Contrastive learning has shown great potential in video representation learning. However, existing approaches fail to sufficiently exploit short-term motion dynamics, which are crucial to various down-stream video understanding tasks. In this paper, we propose Motion Sensitive Contrastive Learning (MSCL) that injects the motion information captured by optical flows into RGB frames to strengthen feature learning. To achieve this, in addition to clip-level global contrastive learning, we develop
more » ... ocal Motion Contrastive Learning (LMCL) with frame-level contrastive objectives across the two modalities. Moreover, we introduce Flow Rotation Augmentation (FRA) to generate extra motion-shuffled negative samples and Motion Differential Sampling (MDS) to accurately screen training samples. Extensive experiments on standard benchmarks validate the effectiveness of the proposed method. With the commonly-used 3D ResNet-18 as the backbone, we achieve the top-1 accuracies of 91.5\% on UCF101 and 50.3\% on Something-Something v2 for video classification, and a 65.6\% Top-1 Recall on UCF101 for video retrieval, notably improving the state-of-the-art.
arXiv:2208.06105v1 fatcat:xgtnmiq7qnhsvfy77jfpdt362y
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