Characterization and snubbing of a bidirectional MCT switch in aresonant AC link converter

The MOS-controlled thyristor (MCT) is emerging as a powerful switch that combines the characteristics of existing power devices. This paper presents a study of switching stresses on the MCT under zero voltage resonant switching. Two MCTs and two diodes are connected to form a bidirectional switch which was used in an AC/AC resonant link inverter. Current and voltage spikes are observed and analyzed with variations in the timing of the MCT switching. Different snubber circuit configurations are investigated to minimize the effect of these transients. Some failure modes of the device are also presented     

Deriving Stopping Rules for the Probabilistic Hough Transform by Sequential Analysis

It is known that Hough transform computation can be significantly accelerated by polling instead of voting. A small part of the data set is selected at random and used as input to the algorithm. The performance of these probabilistic Hough transforms depends on the poll size. Most probabilistic Hough algorithms use a fixed poll size, which is far from optimal since conservative design requires the fixed poll size to be much larger than necessary under average conditions. It has recently been experimentally demonstrated that adaptive termination of voting can lead to improved performance in terms of the error rate versus average poll size tradeoff. However, the lack of a solid theoretical foundation made general performance evaluation and optimal design of adaptive stopping rules nearly impossible. In this paper it is shown that the statistical theory of sequential hypotheses testing can provide a useful theoretical framework for the analysis and development of adaptive stopping rules for the probabilistic Hough transform. The algorithm is restated in statistical terms and two novel rules for adaptive termination of the polling are developed. The performance of the suggested stopping rules is verified using synthetic data as well as real images. It is shown that the extension suggested in this paper to A. Wald's one-sided alternative sequential test (Sequential Analysis,Wiley, New York, 1947) performs better than previously available adaptive (or fixed) stopping rules.     

Modification of a procedure for analytical hydrogenation of edible oils

Unsaturation, an important parameter in edible oils, can be determined by analytical hydrogenation. Recently Brown et al. (3–9) have proposed an “automatic” direct titration method for hydrogenation of various unsaturated organic compounds. Sodium borohydride, introduced through a pressure-actuated mercury valve, was utilized as hydrogen producing reagent, and both the hydrogen and the platinum catalyst were generated in situ. Application of the above method to determination of unsaturation in various edible oils was the subject of the present study. Several shortcomings inherent in the original procedure and apparatus have been overcome by introducing suitable changes. Isopropanol was used as a solvent for the borohydride; the buret was used at the operational stage in the near horizontal position; the end point manometer was filled with Brodie’s solution; and the system was preliminarily flushed with hydrogen from an external source and was operated at a slight overpressure. As a result of those changes, the determined hydrogen iodine values were closer to the expected ones and the standard deviations were appreciably lowered. Gravimetric determinations have confirmed Brown’s observation that the precipitated powder produced by reduction of chloroplatinic acid consists only of pure platinum. Microscopic examinations revealed that a finer structure and better dispersion is obtained when platinum was precipitated on activated carbon as support. This can be conceived with the observed higher over-all reaction rates achieved with the supported catalyst. Presented at the AOCS-ISF World Congress, Chicago, September 1970.     

The gut‐kidney axis in chronic renal failure: A new potential target for therapy

Evidence is accumulating to consider the gut microbiome as a central player in the gut‐kidney axis. Microbiome products, such as advanced glycation end products, phenols, and indoles, are absorbed into the circulation but are cleared by normal‐functioning kidneys. These products then become toxic and contribute to the uremic load and to the progression of chronic kidney failure. In this review, we discuss the gut‐kidney interaction under the state of chronic kidney failure as well as the potential mechanisms by which a change in the gut flora (termed gut dysbiosis) in chronic kidney disease (CKD) exacerbates uremia and leads to further progression of CKD and inflammation. Finally, the potential therapeutic interventions to target the gut microbiome in CKD are discussed.     

Isolation of soybean protein: Effect of processing conditions on yields and purity

The process of soybean-protein isolation, comprising extraction in dilute calcium hydroxide and precipitation with hydrochloric acid at pH 4.5, was evaluated from the viewpoint of the effect of processing conditions on yields and product purity. The course of extraction and the effect of particle size and agitation indicate that the process is quite rapid even when coarse meal is treated under mild agitation. The heattreatment history of the meal is the main factor governing the extraction and isolation yields. The precipitation yield is unaffected by temperature. Two steps of curd washing were found to suffice for maximum product purity. The purity is also improved considerably by preliminary sifting of the meal.     

Distributed algorithms for constructing a minimum-weight spanning tree in a broadcast network

Two distributed algorithms are presented for a network using a common communication channel (e.g. radio) in which all nodes are within signal range and in line of sight of each other: (a) an algorithm to compute all internode distances (in terms of propagation delays) in the network. the algorithm requires only 2 messages per node, and provides each node with the distances to all other nodes. (b) An algorithm for constructing a minimum-weight spanning tree (MST) in such a network. This algorithm starts out with the information provided by (a) and ends with each node possessing the explicit knowledge of the full MST. The algorithm requires at most log₂ N messages per node. The internal processing in each node needsO(N logN) time andO(N) space. All messages required by (a) and (b) contain at most one edge weight plus 2 log₂ N bits. Some possible applications of the algorithms are: position-location, tuning acknowledgement time-out mechanisms, tuning the scheduling functions of access protocols that are sensitive to individual internode propagation delays, and selecting performance effective transmission sequences for round robin access protocols.Yaron I. Gold received the B.Sc. (Cum Laude, 1970) and M.Sc. (1975), both in Electrical Engineering, from the Technion, Israel institute of Technology, and the Ph.D. (1981) in Computer Science, from the University of Minnesota, Minneapolis.From 1970 to 1975 Yaron Gold served as Research and Development Officer in the Israeli Defense Forces, leading a group of several scientists, engineers and technicians. From 1982 to 1984 he was on the faculty of the Department of Electrical Engineering the Department of Electrical Engineering and Computer Science at the University of Connecticut. During that period he also served as consultant for United Technologies Corporation and for Battelle Laboratories. Presently, Dr. Gold is on the faculty of the Computer Science Department at the Technion.His research interests include Computer Networks and Communications, Simulation and Intelligent Systems.Shlomo Moran received the B.Sc. and D.Sc. degrees in mathematics from Technion, Israel Institute of Technology, Haifa, in 1975 and 1979, respectively.From 1979 to 1981 he was assistant professor and a visiting research specialist at the University of Minnesota, Minneapolis. From 1981 to 1985 he was a senior lecturer at the Department of Computer Science, Technion, and from 1985 to 1986 he was a World Trade visitor at IBM Thomas J. Watson Research Center, Yorktown Heights. Currently he is associate professor at the Department of Computer Science, Technion.His research interests include distributed algorithms, computational complexity, combinatorics, graph theory and geometric aspects of communication networks.This work was supported in part by NSF grant ECS-8307186Part of this research was done while this author was with the University of ConnecticutPart of this research was done while this author was with IBM, Thomas J. Watson Research Center     

Maximizing the weighted number of just-in-time jobs in?several two-machine scheduling systems

The problem of maximizing the weighted number of just-in-time jobs in a two-machine flow shop scheduling system is known to be NP\mathcal {NP}-hard (Choi and Yoon in J. Shed. 10:237–243, 2007). However, the question of whether this problem is strongly or ordinarily NP\mathcal{NP}-hard remains an open question. We provide a pseudo-polynomial time algorithm to solve this problem, proving that it is NP\mathcal{NP}-hard in the ordinary sense. Moreover, we show how the pseudo-polynomial algorithm can be converted to a fully polynomial time approximation scheme (FPTAS). In addition, we prove that the same problem is strongly NP\mathcal{NP}-hard for both a two-machine job shop scheduling system and a two-machine open shop scheduling system.     

A correction algorithm for token-passing sequences in mobile communication networks

We present a distributed approximation algorithm for the Traveling Salesman Problem (TSP) in networks that use a broadcast, multiaccess communication channel. The application for which the algorithm was originally designed is maintaining a short token-passing path (which means low scheduling overhead) in radio networks with mobile nodes.The algorithm is adaptive in the sense that it shifts gradually between performing a slight correction of an existing tour and recomputing one from scratch. It can thus be viewed as a generalization, or extension, of conventional TSP algorithms. The proposed algorithm guarantees the same worst-case tour length as the one guaranteed by any conventional from scratch algorithm, yet it is capable of taking advantage of certain node layouts (e.g., geographically clustered nodes) to reduce the cost of computing the path.The correction algorithm is suitable for dynamic graphs with slowly changing edge weights, and for which a Traveling Salesman tour (optimal or approximate) has previously been computed and is deteriorating with time due to the weight changes. The algorithm can be used to refresh the tour whenever it deteriorates beyond a given level, and thus maintain a reasonable average tour length at relatively low computation and communication costs. For a Euclidean graph withn nodes laid out in a bounded area with diameterD, the maximal length of the tour produced by the algorithm is proportional toDn, like the maximal length of an optimal tour in that graph (the two differ by a factor of 2 at the worst case).This work was supported in part by NSF Grant No. ECS-8307186 and in part by ARO Grant No. DAAG29-85-K-0044. Part of this work was done while Y. Gold was with the Department of Electrical Engineering and Computer Science, University of Connecticut, USA. Part of this work was done while S. Moran was with IBM Thomas J. Watson Research Center, Yorktown Heights, NY, USA.     

A correction algorithm for token-passing sequences in mobile communication networks

We present a distributed approximation algorithm for the Traveling Salesman Problem (TSP) in networks that use a broadcast, multiaccess communication channel. The application for which the algorithm was originally designed is maintaining a short token-passing path (which means low scheduling overhead) in radio networks with mobile nodes. The algorithm is adaptive in the sense that it shifts gradually between performing a slight correction of an existing tour and recomputing one “from scratch.” It can thus be viewed as a generalization, or extension, of conventional TSP algorithms. The proposed algorithm guarantees the same worst-case tour length as the one guaranteed by any conventional “from scratch” algorithm, yet it is capable of taking advantage of certain node layouts (e.g., geographically clustered nodes) to reduce the cost of computing the path. The correction algorithm is suitable for dynamic graphs with slowly changing edge weights, and for which a Traveling Salesman tour (optimal or approximate) has previously been computed and is “deteriorating” with time due to the weight changes. The algorithm can be used to “refresh” the tour whenever it deteriorates beyond a given level, and thus maintain a reasonable average tour length at relatively low computation and communication costs. For a Euclidean graph withn nodes laid out in a bounded area with diameterD, the maximal length of the tour produced by the algorithm is proportional toD√n, like the maximal length of an optimal tour in that graph (the two differ by a factor of 2 at the worst case).