Computation of Dielectric Constants and Loss Tangents at ISM Band by Measurements of Transmission Coefficients

1　IntroductionWirelesslocalnetworksareexpandingrapidlyastheresultofincreasingdemandforcomputercom municationsandtheadvancesofdigitalradiosys tems.Newdigitalsystemsarebeingimplementedinmicrowaveandmillimeterwavebands .Whereasthequalityofanaloguesystemsisstronglyrelatedtothereceivedpowerofthesignal,digitalcommunicationsaresensitivetootherperturbations.Inparticular,thedecodingefficiencycanbeimpairedbyintersym bolinterferenceowingtomultipatheffects.Agoodknowledgeofthewidebandchannelisthusneces s…     

Novel mutations in the polyadenine tract of the transforming growth factor beta type II receptor gene are found in a subpopulation of human pancreatic adenocarcinomas

Between November 1994 and January 1997, 42 cases of cyanotic congenital cardiac defects underwent definitive surgery at Matsudo Municipal Hospital. We evaluated 30 cases, each weighing from 7 to 20 kg. The procedures were performed at the age of 9 months to 6 years (mean age-2.4 years). The body weights were 7.7 to 20 kg (mean weight-11.4 kg). The preoperative diagnoses were Tetralogy of Fallot (TOF) in 19 cases, Fontan candidates in 6 and the others in 5. We classified them into 3 groups; Group A--15 cases were completed with non-blood transfusion, Group B--8 cases used only plasma protein fraction and Group C--7 cases used blood transfusion. Cardiopulmonary bypass (CPB) system is a semi-closed circuit and priming volume is 400 to 600 ml. There is no difference among the 3 groups in operative age, body weight, operation time, CPB time, aortic cross clamp time, bleeding and postoperative state. The same results were obtained in minimum base excess and urine output during CPB and the changes of hematocrit and total protein. In Groups A and B, CPB blood was returned to the patient as soon as possible after CPB was weaned, but in Group C, blood transfusion was performed without the return of CPB blood. In all groups, hemodynamics were stable. Retrospectively, it is thought that blood transfusion was not necessary in Group C and the use of the plasma protein fraction was not needed in Group B. In conclusion, the open heart surgery can be performed safely without blood transfusion for cyanotic congenital cardiac defects.     

Recent Advances in Communication and Internet Technology

Telecommunication Systems -     

The CHIP - Peak Detectors for Multistandard Wireless Receivers

Peak detectors (or envelope detectors) are commonly found in modern communication receivers mainly as a building block of automatic gain control (AGC) loops. The main function of the peak detectors is to detect the peak value of an input signal and track the peak over time. In this paper, some of peak detector topologies and their applications in multistandard wireless receivers was presented     

Passivity and passivity breakdown of a zinc electrode in aerated neutral sodium nitrate solutions

The passivation and pitting corrosion behaviour of a zinc electrode in aerated neutral sodium nitrate solutions was investigated by cyclic voltammetry and chronopotentiometry techniques, complemented by ex situ scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) examinations of the electrode surface. Measurements were conducted under different experimental conditions. The potentiodynamic anodic polarization curves do not exhibit active dissolution region due to spontaneous passivation. The passivity is due to the presence of thin film of ZnO on the anode surface. The passive region is followed by pitting corrosion as a result of breakdown of the passive film. SEM images confirmed the existence of pits on the electrode surface. The breakdown potential decreases with an increase in NO₃⁻ concentration and temperature, but increases with increasing potential scan rate. Addition of SO₄²⁻ ions to the nitrate solution accelerates pitting corrosion, while addition of WO₄²⁻ and MoO₄²⁻ ions inhibits pitting corrosion. The chronopotentiometry measurements show that the incubation time for pitting initiation decreases with increasing NO₃⁻ concentration, temperature and applied anodic current density. Addition of SO₄²⁻ ions decreases the rate of passive film growth and the incubation time, while the reverse changes produced by addition of either WO₄²⁻ or MoO₄²⁻ ions.     

On the boundary integral formulation of thermo-viscoelasticity theory

A formulation of the boundary integral equation method for generalized thermo-viscoelasticity is given. Fundamental solutions of the corresponding differential equations are obtained. An outline of the implementation of the boundary element method is discussed for the solution of the above boundary equations. Special emphasis is given to the representation of the primary fields, namely, temperature and displacement.