A Decoupled and Linear Framework for Global Outlier Rejection over Planar Pose Graph

We propose a robust framework for the planar pose graph optimization contaminated by loop closure outliers. Our framework rejects outliers by first decoupling the robust PGO problem wrapped by a Truncated Least Squares kernel into two subproblems. Then, the framework introduces a linear angle representation to rewrite the first subproblem that is originally formulated with rotation matrices. The framework is configured with the Graduated Non-Convexity (GNC) algorithm to solve the two non-convex subproblems in succession without initial guesses. Thanks to the linearity properties of both the subproblems, our framework requires only linear solvers to optimally solve the optimization problems encountered in GNC. We extensively validate the proposed framework, named DEGNC-LAF (DEcoupled Graduated Non-Convexity with Linear Angle Formulation) in planar PGO benchmarks. It turns out that it runs significantly (sometimes up to over 30 times) faster than the standard and general-purpose GNC while resulting in high-quality estimates.Comment: 7 pages, 4 figures. Submitted to the IEEE International Conference on Robotics and Automation (ICRA

Distributed Optimization in Sensor Network for Scalable Multi-Robot Relative State Estimation

Distance measurements demonstrate distinctive scalability when used for relative state estimation in large-scale multi-robot systems. Despite the attractiveness of distance measurements, multi-robot relative state estimation based on distance measurements raises a tricky optimization problem, especially in the context of large-scale systems. Motivated by this, we aim to develop specialized computational techniques that enable robust and efficient estimation when deploying distance measurements at scale. We first reveal the commonality between the estimation problem and the one that finds realization of a sensor network, from which we draw crucial lesson to inspire the proposed methods. However, solving the latter problem in large-scale (still) requires distributed optimization schemes with scalability natures, efficient computational procedures, and fast convergence rates. Towards this goal, we propose a complementary pair of distributed computational techniques with the classical block coordinate descent (BCD) algorithm as a unified backbone. In the first method, we treat Burer-Monteiro factorization as a rank-restricted heuristic for rank-constrained semidefinite programming (SDP), where a specialized BCD-type algorithm that analytically solve each block update subproblem is employed. Although this method enables robust and (extremely) fast recovery of estimates from initial guesses, it inevitably fails as the initialization becomes disorganized. We therefore propose the second method, derived from a convex formulation named anchored edge-based semidefinite programming} (ESDP), to complement it, at the expense of a certain loss of efficiency. This formulation is structurally decomposable so that BCD can be naturally employed, where each subproblem is convex and (again) solved exactly...Comment: Extended technical report (14 pages, 5 figures, 2 tables

Synthesis and Thermoelectric Properties of CuSbS2

Copper antimony sulfide, CuSbS2 nanoparticles have a large potential of being a good thermoelectric material because they are made up of earth abundant elements. Thermoelectric materials can convert thermal energy into electricity, so that the wasted energy can be saved. Also, by using this earth abundant material, we can make thermoelectric materials much cheaper. The hypothesis of this study is that CuSbS2 could have a large Seebeck coefficient, one of the most important factors of thermoelectric materials, because of the complexity of its band structure. The other hypothesis is that thermal transport could be significantly suppressed through nanostructuring. There are three main methods used in this study. First, the synthesis (mass production) of the CuSbS2 nanoparticles was performed by a redox reaction in an oxygen-free environment. The second method is the material characterization including electron microscopy X-ray diffraction and energy dispersion spectroscopy. Finally, the thermoelectric properties characterization was performed, including the measurements of Seebeck coefficients and electrical conductivities. The initial results show comparable thermoelectric performance to other thermoelectric materials made by earth abundant elements. We successfully developed the recipe to synthesize CuSbS2 nanoparticles and our measurements contribute to the knowledge of thermoelectric properties of this material. Further work includes tuning the relative density and carrier concentration to enhance CuSbS2’s thermoelectric properties

Viscosity Analysis of Battery Electrode Slurry.

We report the effects of component ratios and mixing time on electrode slurry viscosity. Three component quantities were varied: active material (graphite), conductive material (carbon black), and polymer binder (carboxymethyl cellulose, CMC). The slurries demonstrated shear-thinning behavior, and suspension properties stabilized after a relatively short mixing duration. However, micrographs of the slurries suggested their internal structures did not stabilize after the same mixing time. Increasing the content of polymer binder CMC caused the greatest viscosity increase compared to that of carbon black and graphite

Organic Solvent Free Process to Fabricate High Performance Silicon/Graphite Composite Anode

Cycling stability is a key challenge for application of silicon (Si)-based composite anodes as the severe volume fluctuation of Si readily leads to fast capacity fading. The binder is a crucial component of the composite electrodes. Although only occupying a small amount of the total composite mass, the binder has major impact on the long-term electrochemical performance of Si-based anodes. In recent years, water-based binders including styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) have attracted wide research interest as eco-friendly and low-cost alternatives for the conventional poly(vinylidene difluoride) (PVDF) binder in Si anodes. In this study, Si-based composite anodes are fabricated by simple solid mixing of the active materials with subsequent addition of SBR and CMC binders. This approach bypasses the use of toxic and expansive organic solvents. The factors of binder, silicon, and graphite materials have been systematically investigated. It is found that the retained capacities of the anodes are more than 440 mAh/g after 400 cycles. These results indicate that organic solvent free process is a facile strategy for producing high performance silicon/graphite composite anodes

The Dunning–Kruger effect: subjective health perceptions on smoking behavior among older Chinese adults

Abstract Background The intrinsic damage and external hazards of smoking are major risk factors for poorer health and are recognized as a global health issue of concern in geriatric health. This study aims to assess the Dunning–Kruger effect through the influence of subjective health perceptions on smoking behavior in older adults. Methods This study used data from the 2018 Chinese Longitudinal Healthy Longevity Survey (N = 9,683) provided by the Center for Healthy Aging and Development Studies at Peking University. A binary logistic model was used to examine whether the Dunning–Kruger effect affects smoking behavior in older adults, and a linear probability model was used as a commentary baseline model for logistic regression to prevent measurement bias. In addition, a mediating analysis was used to examine the mechanisms through which the Dunning–Kruger effect occurs. Results Older adults often overestimated their current health status and underestimated the health risks of smoking, causing the Dunning–Kruger effect to arise from their inadequate self-perceived health (i.e., older adults are more likely to smoke when they have better self-rated health or when hypertension, cardiopathy, stroke, and diabetes have little or no impact on their daily lives). These observations can be explained by the older adults’ subjective health perceptions arising from their ingenuous understanding of their health, which indirectly influences their smoking behavior to some extent. Conclusion Older adults’ self-perceived health was associated with smoking behavior. Public health institutions should improve older adults’ health perceptions so that they objectively understand their own health status

Lessons learned from the 2019-nCoV epidemic on prevention of future infectious diseases.

Only a month after the outbreak of pneumonia caused by 2019-nCoV, more than forty-thousand people were infected. This put enormous pressure on the Chinese government, medical healthcare provider, and the general public, but also made the international community deeply nervous. On the 25th day after the outbreak, the Chinese government implemented strict traffic restrictions on the area where the 2019-nCoV had originated-Hubei province, whose capital city is Wuhan. Ten days later, the rate of increase of cases in Hubei showed a significant difference (p = 0.0001) compared with the total rate of increase in other provinces of China. These preliminary data suggest the effectiveness of a traffic restriction policy for this pandemic thus far. At the same time, solid financial support and improved research ability, along with network communication technology, also greatly facilitated the application of epidemic prevention measures. These measures were motivated by the need to provide effective treatment of patients, and involved consultation with three major groups in policy formulation-public health experts, the government, and the general public. It was also aided by media and information technology, as well as international cooperation. This experience will provide China and other countries with valuable lessons for quickly coordinating and coping with future public health emergencies

Lessons learned from the 2019-nCoV epidemic on prevention of future infectious diseases

© 2020 Institut Pasteur Only a month after the outbreak of pneumonia caused by 2019-nCoV, more than forty-thousand people were infected. This put enormous pressure on the Chinese government, medical healthcare provider, and the general public, but also made the international community deeply nervous. On the 25th day after the outbreak, the Chinese government implemented strict traffic restrictions on the area where the 2019-nCoV had originated—Hubei province, whose capital city is Wuhan. Ten days later, the rate of increase of cases in Hubei showed a significant difference (p = 0.0001) compared with the total rate of increase in other provinces of China. These preliminary data suggest the effectiveness of a traffic restriction policy for this pandemic thus far. At the same time, solid financial support and improved research ability, along with network communication technology, also greatly facilitated the application of epidemic prevention measures. These measures were motivated by the need to provide effective treatment of patients, and involved consultation with three major groups in policy formulation—public health experts, the government, and the general public. It was also aided by media and information technology, as well as international cooperation. This experience will provide China and other countries with valuable lessons for quickly coordinating and coping with future public health emergencies

IL-21 arming potentiates the anti-tumor activity of an oncolytic vaccinia virus in monotherapy and combination therapy

Background Oncolytic viruses (OVs) have shown promise in containing cancer progression in both animal models and clinical trials. How to further improve the efficacy of OVs are intensively explored. Arming OVs with immunoregulatory molecules has emerged as an important means to enhance their oncolytic activities majorly based on the mechanism of reverting the immunosuppressive nature of tumor environment. In this study, we aimed to identify the optimal combination of different OVs and immunomodulatory molecules for solid tumor treatment as well as the underlying mechanism, and subsequently evaluated its potential synergy with other immunotherapies.Methods Panels of oncolytic viruses and cells stably expressing immunoregulatory molecules were separately evaluated for treating solid tumors in mouse model. A tumor-targeted replicating vaccinia virus Tian Tan strain with deletion of TK gene (TTVΔTK) was armed rationally with IL-21 to create rTTVΔTK-IL21 through recombination. CAR-T cells and iNKT cells were generated from human peripheral blood mononuclear cells. The impact of rTTVΔTK-IL21 on tumor-infiltrating lymphocytes was assessed by flow cytometry, and its therapeutic efficacy as monotherapy or in combination with CAR-T and iNKT therapy was assessed in mouse tumor models.Results IL-21 and TTV was respectively identified as most potent immunomodulatory molecule and oncolytic virus for solid tumor suppression in mouse models. A novel recombinant oncolytic virus that resulted from their combination, namely rTTVΔTK-mIL21, led to significant tumor regression in mice, even for noninjected distant tumor. Mechanistically, rTTV∆TK-mIL21 induced a selective enrichment of immune effector cells over Treg cells and engage a systemic response of therapeutic effect. Moreover, its human form showed a notable synergy with CAR-T or iNKT therapy for tumor treatment when coupled in humanized mice.Conclusion With a strong potency of shaping tumor microenvironment toward favoring TIL activities, rTTVΔTK-IL21 represents a new opportunity worthy of further exploration in clinical settings for solid tumor control, particularly in combinatorial strategies with other immunotherapies.One sentence summary IL21-armed recombinant oncolytic vaccinia virus has potent anti-tumor activities as monotherapy and in combination with other immunotherapies