Design sensitivity analysis and optimization of dynamic response

The paper presents methods of design sensitivity analysis and optimization of dynamic response of mechanical and structural systems. A key feature of the paper is the development of procedures to handle point-wise state variable constraints. Difficulties with a previous treatment where such constraints were transformed to equivalent integral constraints are noted and explained from theoretical as well as engineering standpoints. An alternate treatment of such constraints is proposed, developed and evaluated. In this treatment each point-wise state variable constraint is replaced by several constraints that are imposed at all the local max-points for the original constraint function. The differential equations of motion are formulated in the first-order form so as to handle more general problems. The direct differentiation and adjoint variable methods of design sensitivity analysis to deal with the point-wise constraints are presented. With the adjoint variable methods, there are two ways of calculating design sensitivity coefficients. The first approach uses an impulse load and the second approach uses a step load for the corresponding adjoint equation. Since the adjoint variable methods are better for a large class of problems, an efficient computational algorithm with these methods is presented in detail. Optimum results for several problems are obtained and compared with those available in the literature. The new formulation works extremely well as precise optimum designs are obtained.     

Respiratory distress in newborn: treated with ventilation in a level II nursery

The ClearView Uterine Manipulator was compared with the Cohen acorn-tipped cannula for efficacy and safety in patients undergoing laparoscopy at the University of Utah Medical Center. Fifty consecutive patients were randomized by computer to have either the ClearView instrument or the Cohen cannula used as a uterine manipulator (25 patients each). The ClearView manipulator was statistically superior to the Cohen cannula for range of motion in the anterior and posterior sagittal plane (p <0.0001). The Cohen cannula was consistently inserted in less time (p <0.02). There was no statistically significant difference between the instruments in ease of uterine manipulation, ease of dye instillation, percentage of dye leakage from the cervix, overall ease of use, ease of device insertion, and ease of device removal. Two cervical perforations occurred during cervical dilatation in the ClearView manipulator group in patients with cervical stenosis requiring dilatation with metal dilators (os <2 mm). No patients in the Cohen cannula group had cervical stenosis. In that group two cervical lacerations occurred requiring suture ligation. The ClearView instrument provides a greater range of motion, does not require an assistant to maintain uterine position, and allows manipulation without a cervical tenaculum. Its insertion occasionally (36%) required tenaculum placement, uterine sounding, and cervical dilatation, increasing the time of insertion compared with placement of the Cohen cannula. In patients with cervical stenosis, use of a uterine sound and cervical dilatation increase the risk of perforation.     

Throughput analysis in wireless networks with multiple users and multiple channels

We consider the problem of maximizing throughput in a multi-carrier wireless network that employs predictive link adaptation. We explicitly consider the time-penalty incurred due to link adaptation. The contributions of this paper are twofold. Firstly, several high performance algorithms (offline and online) are developed for efficient performance in multiple user and multiple channel environment under the practicable lookahead prediction of one time slot. Secondly, the presented algorithms and heuristics are shown to be competitive by deterministic and probabilistic analyses. Our results show that a modest consumption of resources for channel prediction and link adaptation may result in a significant throughput improvement.     

Electromagnetic acoustic transducer for in-plane and plane-normal velocity measurements

A new electromagnetic acoustic transducer (EMAT) is developed that measures velocities and absolute surface displacements in-plane and plane-normal to the direction of wave propagation. This transducer is flexible in shape and design to conform with irregular surfaces and has unique characteristics of nonresonant frequency response. Tests show that the sensitivity of this EMAT can be increased by increasing the applied magnetic field. Because this transducer is mode selective and nonresonent, its response can be related uniquely to the wave motion. This property is highly desirable for research purposes, though generally not wanted in field monitoring situations.     

Variability of Starch and Sugar Contents in Grains of Sorghum Forages and its Correlation with Tannin and Mineral Matter Content

Ninteen promising strains of fodder sorghum were selected for the present study. The starch content in the seed varied from 42.68 to 68.31%, total sugars from 3.13 to 7.81%, mineral matter from 1.12 to 4.09%. The amylose content was approximately in the range of 12 — 13% and amylose : amylopectin ratio was 1:4 to 1:10. The tannin content ranged from 0.23 to 3.73 mg/g of seed and it was high in non sweet varieties and low in sweet varieties. There was not much difference in the sugar content of sweet and non sweet varieties. The protein content of the seed varied from 8.31 to 14.41%. Starch content of seed was significantly negatively correlated with tannin and mineral matter content of the seed (−0.595 and −0.491) but tannin content was positively correlated with mineral matter content and was significant ( + 0.581). A genetic manipulation of breeding material can bring about high amylose and protein varieties.