Transient propagation of anti-plane cracks opened by time varying loads

The problem of an anti-plane crack opened by a time varying concentrated load at the origin, and propagating self-similarly in an elastic body was treated. The analysis is based on Chaplygin's transformation and the solution is effected by using the conformal mapping technique. The problem was reduced to a mixed boundary value problem for an analytic function in the half-plane, which is solvable by the Keldysh-Sedov formula.

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Résumé On traite du problème de l'ouverture, puis de la propagation, d'une fissure antiplanaire dans un corps élastique, sous l'effet d'une charge concentrée à son origine, et caractérisée par des variations dans le temps. L'analyse est basée sur une transformation de Chaplygin, solutionnée en recourant à une technique de représentation conforme. Le problème a été réduit à un problème mixte de valeurs aux limites d'une fonction analytique dans le demi-plan, laquelle peut être résolue par une fonction de Keldish-Sedov.

     

Gain, phase imbalance, and phase noise effects on error vector magnitude

The error vector magnitude (EVM) is extensively applied as a measure of communication systems' performance. In this paper, the effects of gain, phase imbalance, and phase noise on EVM are examined. The work is focused on single-carrier, linear, and memoryless modulated signals, such as phase-shift keying and quadrature amplitude modulation (QAM). The EVM is calculated under the assumption that the transmitted signal consists of zero-mean uncorrelated inphase and quadrature components that are corrupted by additive white Gaussian noise. The contributions of this paper are as follows. First, an expression for the EVM is derived using a simple model that accounts for linear transmitter and receiver imperfections, inspired by the works of Cavers and Liao, 1993. Second, a union bound on the symbol error rate (SER) is derived. The root mean square EVM is shown to be independent of the constellation shape. The SER, however, is sensitive to the individual transmitted symbols and, therefore, the constellation shape. The resulting equations are used to examine the relation between EVM, sideband suppression, and phase noise.     

Paclitaxel by 96-hour continuous infusion in combination with cisplatin: a phase I trial in patients with advanced lung cancer

PURPOSE: To determine the maximum-tolerated dose (MTD) of paclitaxel administered by 96-hour continuous infusion in combination with cisplatin, to determine if the addition of granulocyte colony-stimulating factor (G-CSF) permits significant paclitaxel dose escalation, and to assess the toxicity and preliminary activity of this combination in patients with advanced lung cancer. PATIENTS AND METHODS: Fifty patients with untreated lung cancer were enrolled: 42 had advanced non-small-cell lung cancer (NSCLC) and eight had extensive-stage small-cell lung cancer (SCLC). Patients received paclitaxel doses of 100 to 180 mg/m2/96 hours and cisplatin doses of 60 to 80 mg/m2 as a single 30-minute bolus injection at the end of the paclitaxel infusion. RESULTS: Two of six patients experienced dose-limiting neutropenia at a dose of paclitaxel 140 mg/m2/96 hours and cisplatin 80 mg/m2. With G-CSF support, one of three patients experienced both dose-limiting mucositis and fatal neutropenic sepsis at a dose of paclitaxel 180 mg/m2/96 hours and cisplatin 80 mg/m2. Significant peripheral neuropathy developed in five patients and occurred after six or more cycles of therapy. Thirty-three of 42 patients with NSCLC had measurable disease; the objective response rate was 55%, with two complete responses and 16 partial responses. For all 42 patients with NSCLC, the median time to progression and median survival duration were 5 months and 10 months, respectively. The actuarial 1-year survival rate was 41%. Of eight SCLC patients, four responded to therapy, and the median survival duration for all SCLC patients was 11 months. CONCLUSION: The MTD without G-CSF is paclitaxel 120 mg/m2/96 hours and cisplatin 80 mg/m2, and the MTD with G-CSF is paclitaxel 160 mg/m2/96 hours and cisplatin 80 mg/m2. Infusional paclitaxel with cisplatin is well tolerated and active in patients with advanced NSCLC.     

Throughput properties of fair policies in ring networks

Considers a slotted ring in which simultaneous transmission of messages by different stations is allowed, a property referred to as spatial reuse. Ring networks with spatial reuse can achieve significantly higher throughput than standard token rings but they also introduce the possibility of starvation for some nodes on the ring. To alleviate this problem, various policies have been suggested in the literature. The present objective is to characterize the node throughputs achievable by general transmission policies in ring networks with spatial reuse and then to evaluate the throughput trade-off for a class of policies that has been proposed in the literature in order to avoid starvation. Specifically, the authors study a policy that is based on the idea of allocating transmission quotas to the nodes. Each node is guaranteed transmission of his quota within a specified interval. The authors show that by appropriately allocating the quotas, policies that satisfy general optimality criteria-in particular criteria related to fairness-can be designed. They also study the asymptotic behavior of the quota policy when either the quotas or the number of nodes increase     

On a hybrid method to determine strain fields around propagating cracks

The moving singularity of the crack tip in a plane-stress plate causes a highly dynamic stress field of varying intensity with time, throughout the period of the propagation of the crack. This dynamic stress field results in a considerable change of the mechanical and optical properties of a strain-rate dependent material. An analysis of this varying dynamic stress field was presented in this paper which contradicts assumptions and simplifications introduced in a previous paper [7], referring to the same problem. For the experimental determination of the $\text{K}{}^{\mathrm{d}}{}_{\mathrm{I}}\text{-}\text{factor}$ the optical method of the dynamic caustics was utilized in combination with a high-speed camera and a comparison was sketched between the possibilities of this method and the strain-gauge method used in Ref. [7].     

A full sensing window Random-Access algorithm for messages with strict delay constraints

We consider the Channel Multiple-Access problem for messages with strict delay constraints. The constraints are represented by an upper bound on the transmission delays. For this problem, and for binary collision-noncollision feedback per slot, we present a simple full sensing window Random-Access algorithm. We analyze the algorithm and we compute the fraction of maintained traffic and the expected delay for the successfully transmitted packet, for various input Poisson intensities and various values of the bound on the transmission delays.