Distributed Scheduling for Multi-Hop Wireless Networks

We study the performance of greedy scheduling in multihop wireless networks where the objective is aggregate utility maximization. Following standard approaches, we consider the dual of the original optimization problem. Optimal scheduling requires selecting independent sets of maximum aggregate price, but this problem is known to be NP-hard. We propose and evaluate a simple greedy heuristic. We suggest how the greedy heuristic can be implemented in a distributed manner. We evaluate an analytical bound in detail, for the special case of a line graph and also provide a loose bound on the greedy heuristic for the case of an arbitrary graph.

Studio portrait of the wood merchant Hermann Judey with his stepson Paul Portraits Family

Paul was the son from a previous marriage of Hermann's first wife Olga Judey nee Fischmann

Judey family playing cricket Portraits Family

l-r: Hermann (father), Mary (Miriam), Olga (mother), Lydia, Sina and Jacob

Studio portrait of Hermann (Lazar Hirsch) Judey, his father Joseph (Mitskun) Judey, and Hermann's cousin Vladimir (Valodya) Barosin seated around a chess table; Riga Portraits Family

Hermann (Lazar Hirsch) Judey, born 1878 Riga and died 1959 New York; Joseph (Mitskun) Judey, born 1854 Vilna and died 1931 Berlin

Protection and Switching-Aid Networks for Transistor Bridge Inverters

The present trend in the industry is towards the use of power transistors in the development of efficient Pulsewidth Modulated (PWM) inverters, because of their operation at high frequency, simplicity of turn-off, and low commutation losses compared to the technology using thyristors. But the protection of power transistors, minimization of switching power loss, and design of base drive circuit are very important for a reliable operation of the system. The requirements, analysis, and a simplified procedure for calculation of the switching-aid network components are presented. The transistor is protected against short circuit using a modified autoregulated and autoprotection drive circuit. The experimental results show that the switching power loss and voltage stress in the device can be reduced by suitable choice of the switching-aid network component values.

Henry Marx shining shoes to earn money for his family; Washington Heights, New York Portraits Children

Henry Marx was born in Michelstadt/Hessen and emigrated to New York with his family in early 1937 when he was nine years old. He went to school but also delivered newspapers and shined shoes to help his family financially as his father only worked whatever odd jobs he could during the war years. Going from store to store shining shoes on weekends was Henry's main source of income. He had to wake up early in order to reserve the spot shown in this photograph, competing with a father and two sons who traveled from Brooklyn to Washington Heights to shine shoes.

Exterior view of the Boehm family hat factory; Novy Jicin, Czech Republic Businesses

Tovarna na Klobouky Fv. Boehm

Erich Gustav Baum in the drivers seat of a car with his wife Grete nee Dublon and their daughter Ilse Baum in the back seat Portraits Family

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Ilse Baum's class portrait Portraits Family

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View of Muensterstrasse including Erich Gustav Baum's haberdashery store (Waesche Baum); Rheine i.W. Portraits Family

The shop was shut down by the Nazis several times during the 1930s

Grete Baum nee Dublon assisting a customer in her husband Erich Gustav Baum's haberdashery store (Waesche Baum); Muensterstrasse, Rheine i.W. Portraits Family

The shop was shut down by the Nazis several times during the 1930s

Portrait of the six Baum family siblings Portraits Family

Standing are Fritz, Joseph and Lilly. The youngest is Hans. Erich is seated center and Walter is seated on the far right.

Fanny and Hugo Eichenwald with two of their three children, Fritz and Hanne outside of their home; Rheine Portraits; Family

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