ASYMPTOTIC EFFICIENCY OF THE SAMPLE COVARIANCES IN A GAUSSIAN STATIONARY PROCESS

Abstract. This paper deals with the asymptotic efficiency of the sample autocovariances of a Gaussian stationary process. The asymptotic variance of the sample autocovariances and the Cramer–Rao bound are expressed as the integrals of the spectral density and its derivative. We say that the sample autocovariances are asymptotically efficient if the asymptotic variance and the Cramer–Rao bound are identical. In terms of the spectral density we give a necessary and sufficient condition that they are asymptotically efficient. This condition is easy to check for various spectra.     

Basic probabilistic considerations on safety of prestressed concrete pressure vessels

The purpose of the present study is to lay the foundation for the probabilistic safety analysis pertinent to prestressed concrete pressure vessels of nuclear generating stations. We place a major emphasis on the consistency with which various aspects of structural and statistical significance are analyzed and then combined into a probabilistic formulation amenable to practical risk assessment and assurance. In particular (1) prestressed concrete pressure vessels subjected to loads of various temporal nature are considered, (2) the probabilistic algebra used in risk assessment is basically that of the second moment-first order approximation, and (3) the method thus established is applied to reliability analysis of prestressed concrete reactor vessels (PCRVs) to estimate the probability level of ultimate failure. The result of the present study indicating the probability level of the vessel reliability depends entirely on the assumptions concerning statistical aspects of loading conditions and resisting capacities of the vessel and on the approximations in relation to stress and structural analysis and ultimate failure conditions. Therefore, the resulting probability values are illustrative and comparative rather than factual at this time. The authors are solely responsible for the content of this paper which does not represent the official view of the USAEC.     

EFFECT OF INTERMITTENT HEATING ON DRYING-INDUCED STRAIN-STRESS OF MOLDED CLAY

ABSTRACT

Parametric analyses of the strain-stress in the drying process are performed to study the influence of the intermittent drying on the behaviors of drying-induced strain-stress and deformation as well as the drying characteristic. The transient three-dimensional problem of strain-stress and heat and moisture transfer in a slab is solved simultaneously by the finite element method. The dimensionless parameters are introduced to generalize the problem in the conservation equations of heat and moisture transfer. The intermittent drying is modeled by applying periodically smaller and larger Biot numbers to the boundary conditions. The maximum tensile and compressive stresses fluctuate, and fall remarkably during the smaller Biot number period when a slab is heated intermittently. The peak stress of the fluctuation exceeds beyond the case in the continuous healing where the overall drying rate is almost equivalent to that in the intermittent beating, but the reduction of the stresses takes place rapidly in the low heating period.     

Acid-dyeable acrylic fibres copolymerised with amino alkyl methacrylates for differential cross-dyeing

The equilibrium adsorption of acid dyes on acrylic fibres copolymerised with dimethyl amino ethyl methacrylate has been investigated. A typical characteristic of this type of fibre is its excellent stable dyeability over a wide pH range. This is due to the strong basicity of alkylamino groups in the copolymerised component, which makes it possible to dye the fibre thoroughly even in a weakly acidic dyebath using a normal dyeing processes of acrylic fibre with cationic dye. Consequently it is useful for differential cross-dyeing in a single dyebath.     

DRYING OF CLAY AND NONCLAY MEDIA : HEAT AND MASS TRANSFER AND QUALITY ASPECTS

The researches on drying of clay and nonclay media are briefly reviewed and the role of drying in the manufacturing process is summarized. The drying process must be carefully controlled to maintain the desired product configuration. Inefficient completion of drying and poor operation of the dryer influence directly the product quality. The importance of R&D on the heat and moisture transfer phenomena, shrinkage mechanisms, deformation behavior, strain-stress relations and the internal pressure in the media during drying is stressed. Suggestions are given for further improvement of the drying process and improved design of the molding and casting processes for higher product quality     

R & D Needs - Drying of Ceramics

ABSTRACT

New research and development needs for the drying of ceramics are prooosed. The researches on the ceramic drying are briefly reviewed and the role of the drying in the ceramic production process iS summarized. The drying must deal with molded materials and the problem is of significant difference from another drying with particulate materials. It means that the drying must be performed with keeping the molded feature and the insufficient completion of drying and the careless operation influence directly on the product quality The importnance of the R & D on the heat and moisture transfer. shrinking mechanism. the deformation behavior and the strain-stress formation in the molded clay issuggested. The subjects are also pointed out for the further improvement of the ceramic drying process and the precise design of molding with high quality.     

Programmed High‐Hole‐Mobility Supramolecular Polymers from Disk‐Shaped Molecules

In this paper a simple, casting solution technique for the preparation of two‐dimensional (2D) arrays of very‐high molecular weight (MW) 1D‐Pc supramolecular inorganic polymers is described. The soluble fluoroaluminium tetra‐tert‐butylphthalocyanine (ttbPcAlF) is synthesized and characterized, which can be self‐assembled to form 2D arrays of very‐high‐MW 1D‐Pc supramolecular inorganic polymers. High‐resolution transmission electron microscopy (HRTEM) demonstrates that the 1D‐ttbPcAlF, having a cofacial ring spacing of ～0.36 nm and an interchain distance of ～1.7 nm, self‐assembles into 2D‐nanosheets (～140 nm in length, ～20 nm in width, and equivalent to MW of 3.2 × 10⁵ g mol^?1). The film cast from a 1,2‐dichloroethane (DCE) solution shows a minimum hole‐mobility of ～0.3 cm² V^?1 s^?1 at room temperature by flash‐photolysis time‐resolved microwave conductivity (TRMC) measurements and a fairly high dark dc‐conductivity of ～1 × 10^?3 S cm^?1.     

Decision Support for DCs Location and Distribute Range Planning: Case Study in Asia-Pacific Region

A major concern is to locate manufacturing plants and/or distribution centers to serve the needs of consumers widely and rapidly with reasonably distributive cost and flexible delivery time. The purpose of this research is to help enhance a decision support for three distribution center locations with different ranges of area in order that the distributors are able to serve appropriately the retailers in twelve large cities or capitals of the nine countries in Asia-Pacific region. The researcher applies the theory of supply chain and logistics management systems with Excel, Visual Basic and Genetic Algorithms programs to find the research results. The research results revealed that the interfaces of Excel, Visual Basic, and Genetic Algorithms programs helped decision support in distribution range selection for 3 distribution center locations. Each of which had different ranges of area for distribution with a rapidly, flexibly distributed time. However, variables resulting in a decision-making should be adjusted under certain circumstances for more reliable, specific needs.