Multistage bayesian autonomy for high‐precision operation in a large field

This paper presents a generalized multistage bayesian framework to enable an autonomous robot to complete high‐precision operations on a static target in a large field. The proposed framework consists of two multistage approaches, capable of dealing with the complexity of high‐precision operation in a large field to detect and localize the target. In the multistage localization, locations of the robot and the target are estimated sequentially when the target is far away from the robot, whereas these locations are estimated simultaneously when the target is close. A level of confidence (LOC) for each detection criterion of a sensor and the associated probability of detection (POD) of the sensor are defined to make the target detectable with different LOCs at varying distances. Differential entropies of the robot and target are used as a precision metric for evaluating the performance of the proposed approach. The proposed multistage observation and localization approaches were applied to scenarios using an unmanned ground vehicle (UGV) and an unmanned aerial vehicle (UAV). Results with the UGV in simulated environments and then real environments show the effectiveness of the proposed approaches to real‐world problems. A successful demonstration using the UAV is also presented.     

The Trade-Off Between Performance and Security of Virtualized Trusted Execution Environment on Android

Nowadays, with the significant growth of the mobile market, security issues on the Android Operation System have also become an urgent matter. Trusted execution environment (TEE) technologies are considered an option for satisfying the inviolable property by taking advantage of hardware security. However, for Android, TEE technologies still contain restrictions and limitations. The first issue is that non-original equipment manufacturer developers have limited access to the functionality of hardware-based TEE. Another issue of hardware-based TEE is the cross-platform problem. Since every mobile device supports different TEE vendors, it becomes an obstacle for developers to migrate their trusted applications to other Android devices. A software-based TEE solution is a potential approach that allows developers to customize, package and deliver the product efficiently. Motivated by that idea, this paper introduces a VTEE model, a software-based TEE solution, on Android devices. This research contributes to the analysis of the feasibility of using a virtualized TEE on Android devices by considering two metrics: computing performance and security. The experiment shows that the VTEE model can host other software-based TEE services and deliver various cryptography TEE functions on the Android environment. The security evaluation shows that adding the VTEE model to the existing Android does not add more security issues to the traditional design. Overall, this paper shows applicable solutions to adjust the balance between computing performance and security.     

Noise correlation in dual-collector magnetotransistors

Experimental results of low frequency (1/f) noise in magnetic-field-sensitive dual-collector bipolar transistors are presented that show a strong positive correlation between the noise voltages (converted from corresponding fluctuations in the currents) of the collectors. Hence, operating the magnetotransistor in a differential mode yields very favorable signal-to-noise ratios, even for low magnetic sensitivity. Calculations performed for a magnetotransistor with a sensitivity of only 0.06/T yields a field resolution of 25 nT/√Hz at 1 kHz, in contrast to 14 μT/√Hz in single-ended operation     

Design considerations for 60 GHz CMOS radios

With the availability of 7 GHz of unlicensed spectrum around 60 GHz, there is a growing interest in using this resource for new consumer applications requiring very high-data-rate wireless transmission. Historically, the cost of the 60 GHz electronics, implemented in the compound semiconductor technology, has been prohibitively expensive. A fully integrated CMOS solution has the potential to drastically reduce costs enough to hit consumer price points. System, circuit, and device-level barriers to a low-cost 60 GHz CMOS implementation are described, potential solutions are explored, and remaining challenges are discussed.     

Understanding MIDI. The key to creating and conducting the music toyour own MTV video

The Musical Instrument Digital Interface (MIDI) specifies the standard hardware and data format that allow devices to communicate with one another. Developed by researchers in Japan, MIDI Specification 1.0 made its debut in 1983. Soon afterwards, Roland introduced the MPU-401 (MIDI Processor Unit model 401), which gave PC users the power of MIDI. By providing an affordable way to interconnect musical devices, MIDI opened the door to the music world for computer users     

Mass transfer variation within a packed bed and its relation to liquid distribution

The limiting current method is applied to characterize the local mass transfer in the axial, radial and angular directions throughout a packed bed of Pall rings. This is expressed in terms of the particle-to-fluid mass transfer coefficient of ferricyanide ions obtained from the limiting currents measured during its reduction to ferrocyanide at different locations in the bed. Particular focus is placed on the variability of the mass transfer coefficient with position in terms of the quantity MT_VAR, equivalent to the normalized deviation of the function Sh/Sc^0.33. The results confirm those reported by other researchers using more traditional liquid collection and tracer methods. Mass transfer coefficients throughout the bed closely follow normal distributions for the range of Re values investigated. When a multipoint distributor is used, MT_VAR is already low at the lowest flow rate (Re=95) considered and remains unchanged with any further increase in flow rate. In the case of a single-point distributor, on the other hand, MT_VAR decreases with increasing flow rate, but always remains significantly higher than that observed with the multipoint distributor. Moreover, the MT_VAR value depends on whether irrigated or full flow conditions prevail and on the cross-sectional area of the sampling electrodes, suggesting that local mass transfer variations are caused by local liquid velocity variations once the Pall rings are sufficiently wetted.     

SHAPES: A novel approach for learning search heuristics inunder-constrained optimization problems

Although much research in machine learning has been carried out on acquiring knowledge for problem-solving in many problem domains, little effort has been focused on learning search-control knowledge for solving optimization problems. This paper reports on the development of SHAPES, a system that learns heuristic search guidance for solving optimization problems in intractable, under-constrained domains based on the Explanation-Based Learning (EBL) framework. The system embodies two new and novel approaches to machine learning. First, it makes use of explanations of varying levels of approximation as a mean for verifying heuristic-based decisions, allowing heuristic estimates to be revised and corrected during problem-solving. The provision of such a revision mechanism is particularly important when working in intractable and under-constrained domains, where heuristics tend to be highly over-generalized, and hence at times will give rise to incorrect results. Second, it employs a new linear and quadratic programming-based weight-assignment algorithm formulated to direct search toward optimal solutions under best-first search. The algorithm offers a direct method for assigning rule strengths and, in so doing, avoids the need to address the credit-assignment problem faced by other iterative weight-adjustment methods     

Effect of the lactoperoxidase system against three major causal agents of disease in mangoes

The antibacterial activity of the lactoperoxidase system (LPS) on the growth of Xanthomonas campestris, the causal agent of bacterial black spot in mangoes, Botryodiplodia theobromae, the causal agent of stem-end rot disease in mangoes, and Colletotrichum gloeosporioides, the causal agent of anthracnose disease in mangoes, was determined during culture at 30 degrees C and at several pH values (4.5, 5.5, and 6.5). When the results of using the LPS were compared with those from control cultures without the LPS reagents, the growth of the three microorganisms was totally inhibited in all of the conditions tested. Viability tests enumerating cultivable cells of X. campestris showed that the LPS had a bactericidal effect, whatever the pH value. This effect is faster at pH 5.5, corroborating the results reported in the literature (optimal pH for the LPS efficiency). Further, we proved that hydrogen peroxide alone had little inhibition effect on the growth of the microorganisms studied. This compound is essentially used to convert thiocyanate into hypothiocyanate during the lactoperoxidase reaction. The potential of the LPS for the postharvest treatment of the fruits for controlling microbial diseases was thus demonstrated. Nevertheless, further studies are needed on fresh fruits before envisaging any application.