Search Results (4)

Motion segmentation is one of the fundamental steps for detection, tracking, and recognition, and it can separate moving objects from the background. In this paper, we propose a spatial-motion-segmentation algorithm by fusing the events-dimensionality-preprocessing algorithm (EDPA) and the volume of warped events (VWE). The EDPA consists of depth estimation, linear interpolation, and coordinate normalization to obtain an extra dimension (Z) of events. The VWE is conducted by accumulating the warped events (i.e., motion compensation), and the iterative-clustering algorithm is introduced to maximize the contrast (i.e., variance) in the VWE. We established our datasets by utilizing the event-camera simulator (ESIM), which can simulate high-frame-rate videos that are decomposed into frames to generate a large amount of reliable events data. Exterior and interior scenes were segmented in the first part of the experiments. We present the sparrow search algorithm-based gradient ascent (SSA-Gradient Ascent). The SSA-Gradient Ascent, gradient ascent, and particle swarm optimization (PSO) were evaluated in the second part. In Motion Flow 1, the SSA-Gradient Ascent was 0.402% higher than the basic variance value, and 52.941% faster than the basic convergence rate. In Motion Flow 2, the SSA-Gradient Ascent still performed better than the others. The experimental results validate the feasibility of the proposed algorithm. Full article

Place-based policies refer to government efforts to enhance the economic performance of an area within its jurisdiction. Applying various difference in differences strategies, this study evaluates the neighborhood effects of a place-based policy—the Economic Development Priority Areas (EDPA) of Atlanta, Georgia, USA. Since the census block groups are locally defined and the boundaries may change over time, we defined the neighborhoods by creating a set of 0.25-mile- diameter circles evenly distributed across Atlanta, and used the created buffers as the comparison unit. The empirical estimates showed that EDPA designation significantly reduced poverty rate and increased housing price of EDPA neighborhoods but had no beneficial effects on population size and employment rate. The heterogeneous analysis with respect to different initial economic status of the neighborhoods showed a relative larger and significant effect of EDPA designation on low-income neighborhoods. The increasing labor demand induced by EDPA designation in low-income neighborhoods attracted more population to migrate in and put upward pressure on housing prices. The estimation results are robust when replacing the 0.25-mile-diameter circle neighborhoods with 0.5-mile-diameter circle neighborhoods. Although we found some positive effects of the EDPA program in Atlanta, it would be misguided to assume similar effects occur in other areas implementing place-based policies. Full article

Physical layer key generation (PKG) has become a research focus as it solves the key distribution problem, which is difficult in traditional cryptographic mechanisms. Information reconciliation is a critical process in PKG to obtain symmetric keys. Various reconciliation schemes have been proposed, including the error detection protocol-based approach (EDPA) and error correction code-based approach (ECCA). Both EDPA and ECCA have advantages and drawbacks, regarding information leakage, interaction delay, and computation complexity. In this paper, we choose the BBBSS protocol from EDPA and BCH code from ECCA as a case study, analyzing their comprehensive efficiency performance versus pass number and bit disagreement ratio (BDR), respectively. Next, we integrate the strength of the two to design a new hybrid information reconciliation protocol (HIRP). The design of HIRP consists of three main phases, i.e., training, table lookup, and testing. To comprehensively evaluate the reconciliation schemes, we propose a novel efficiency metric to achieve a balance of corrected bits, information leakage, time delay, and computation time, which represents the effectively corrected bits per unit time. The simulation results show that our proposed method outperforms other reconciliation schemes to improve the comprehensive reconciliation efficiency. The average improvement in efficiency is 2.48 and 22.36 times over the BBBSS and BCH code, respectively, when the range of the BDR is from 0.5% to 11.5%. Compared to the BBBSS protocol and the BCH code, HIRP lies at a mid-level in terms of information leakage and computation time cost. Besides, with the lowest time delay cost, HIRP reaches the highest reconciliation efficiency. Full article

Phosphonate ligands demonstrate strong affinity for metal ions. However, there are several cases where the phosphonate is found non-coordinated to the metal ion. Such compounds could be characterized as salts, since the interactions involved are ionic and hydrogen bonding. In this paper we explore a number of such examples, using divalent metal ions (Mg²⁺, Ca²⁺, Sr²⁺ and Ni²⁺) and the phosphonic acids: p-aminobenzylphosphonic acid (H₂PABPA), tetramethylenediamine-tetrakis(methylenephosphonic acid) (H₈TDTMP), and 1,2-ethylenediphosphonic acid (H₄EDPA). The compounds isolated and structurally characterized are [Mg(H₂O)₆]·[HPABPA]₂·6H₂O, [Ca(H₂O)₈]·[HPABPA]₂, [Sr(H₂O)₈]·[HPABPA]₂, [Mg(H₂O)₆]·[H₆TDTMP], and [Ni(H₂O)₆]·[H₂EDPA]·H₂O. Also, the coordination polymer {[Ni(4,4’-bpy)(H₂O)₄]·[H₂EDPA]·H₂O}_n was synthesized and characterized, which contains a bridging 4,4’-bipyridine (4,4’-bpy) ligand forming an infinite chain with the Ni²⁺ cations. All these compounds contain the phosphonate anion as the counterion to charge balance the cationic charge originating from the metal cation. Full article