On relating the reference stress, limit load and the ASME stress classification concepts

This paper discusses the relationship between the concepts of reference stress, limit load and the ASME stress classification framework, as it applies to common mechanical components and structures. The relationship is based on the underlying notion of load-control.

The reference stress method, which has been used mainly in the UK, attempts to correlate creep deformations in a structure with the results of a uniaxial creep test. It has been observed that the reference stress is relatively insensitive to material parameters characterizing creep behaviour. The method has been widely used in the design and life assessment of nuclear as well as conventional components. Specifically, it has been applied to problems pertaining to creep growth, rupture damage, creep buckling, and more recently, elastic-plastic fracture toughness.

Determination of the reference stress is not always a simple task. An approximate method of its determination relies on prior knowledge of limit loads for various configurations and loadings. The drawback, of course, is that there is a reliance on the available catalogue of limit loads. Rather than attempting to ‘fit someone into a garment’, this paper discusses a new and a direct procedure for reference stress determination using the GLOSS R-Node method. The reference stress is determined for some pressure component configurations. The ideas are extended to the ASME stress classification framework, and the various stress categories are discussed.     

New directions in subband coding

Two very different subband coders are described. The first is a modified dynamic bit-allocation-subband coder (D-SBC) designed for variable rate coding situations and easily adaptable to noisy channel environments. It can operate at rates as low as 12 kb/s and still give good quality speech. The second coder is a 16-kb/s waveform coder, based on a combination of subband coding and vector quantization (VQ-SBC). The key feature of this coder is its short coding delay, which makes it suitable for real-time communication networks. The speech quality of both coders has been enhanced by adaptive postfiltering. The coders have been implemented on a single AT&T DSP32 signal processor     

Computer-aided optimal design of a polar-based template digitizer-NC contouring system—II. Dynamic analysis

This paper presents the computer-aided optimal design of a template digitizer-NC contouring system which utilizes a set of polar coordinates. The system can operate both as a copying machine or as a numerical control (NC) machine. Part I of the paper describes the proposed system and its salient features. It also analyzes the contouring error due to the incremental approximation of the contour. This error is dependent on the relative location of the contour pole from the machine pole. An objective function relating the area error to the position of the contour is derived and an optimization procedure to minimize this error is outlined. Test results of an attempt to locate the poles of three test contours for minimum error are then presented.     

Pseudo-analog speech transmission in mobile radio communicationsystems

A low-complexity pseudo-analog speech transmission scheme is proposed for portable communications. It uses a speech coder based on adaptive differential pulse code modulation (ADPCM) in combination with a multilevel digital modulation technique such as M-ary DPSK or M-ary FSK and features low quantization noise, bandwidth efficiency, and robustness to transmission errors. A nonsymmetric M -ary DPSK scheme called skewed M-ary DPSK is proposed to enhance the noisy channel performance. Comparison to conventional analog FM and a digital speech transmission scheme using adaptive predictive coding and forward error correction (FEC) based on convolutional coding shows that the pseudo-analog system has the best objective signal-to-noise ratio performance under most channel conditions. Informal subjective evaluations rate the digital system superior to the pseudo-analog scheme for bad channels and conversely for good channels. It is concluded that the pseudo-analog system can be designed with low delay and high speech quality for good channels with high spectral efficiency     

Antrochonal polyp: a case report of treatment with intranasal steroids

The aetiology of antrochonal polyps is unknown. We report one case where treatment with topical intranasal cortico-steroids was successful. We are not aware of any previous reports of medical treatment.     

A theoretical study of parallel flow condensation with interfacial drag in an annulus

The in-tube condensation model of Bae, Maulbetsch and Rohsenow (BMR) is extended to condensation in an annulus with coolant on the tube side. An iterative calculation procedure is developed and used for predicting the variations of local condensing heat transfer coefficient, quality and wall temperature with condenser length for the systems-steam and Freon-12. Comparison of the predictions with Shah's correlation suggests the applicability of BMR's model for the annulus condensation.     

The Architecture of the Dalí Main-Memory Storage Manager

Performance needs of many database applicationsdictate that the entire database be stored in main memory.The dali system is a main memory storage manager designed toprovide the persistence, availability and safety guarantees one typically expects from a disk-resident database, while at the same time providing very high performance by virtue of being tuned to support in-memory data.User processes map the entire database into their address space andaccess data directly, thus avoiding expensive remote procedure calls andbuffer manager interactionstypical of accesses in disk-resident commercial systems available today.dali recovers the database to a consistent state in the case of system as well as process failures. It alsoprovides unique concurrency control and memory protection features, aswell as ordered and unordered index structures. Both object-oriented and relational database management systems have beenimplemented on top of dali. dali provides access to multiple layers ofapplication programming interface, including its low-level recovery,concurrency control and indexing components as well as its high-levelrelational component. Finally, various features of dali can be tailored tothe needs of an application to achieve high performance–for example,concurrency control and logging can be turned off if not desired, enablingdali to efficiently support applications that requirenon-persistent memory-resident data to be shared by multiple processes.