Hierarchical optimisation for non-linear dynamical systems with non-separable cost functions

In this paper the previous hierarchical optimisation algorithm of Hassan and Singh for non-linear interconnected dynamical systems with separable cost functions is extended to the case of non-linear and non-separable cost functions. This ensures that any decomposition could be used and makes the new algorithm suitable for the optimisation of general non-linear problems.     

Hardened slag–cement pastes of various porosities. III. Surface area in relation to pore structure

The total surface areas, total pore volumes, and the distribution of pore surface and pore volume in pores of different sizes were determined on the hardened slag-cement pastes. Adsorption isotherms of four different adsorbates, namely water, methanol, nitrogen and cyclohexane, were used for surface area and pore structure determinations. The results obtained indicated that water can penetrate into the total pore system, namely both the micropores and the wide pores; whereas methanol can measure wide pores and some of the micropores; moreover, nitrogen and cyclohexane molecules tend to measure only wider groups of pores. The indication gained from this result is that the molecular sieve property plays the most significant role in surface area and pore structure determinations of the hardened cement pastes. The polarity of the molecules seems to be important at low relative vapour pressures, and at high pressures it causes expansion of the pastes.     

A digitally programmable temperature controller based on aphase-locked loop

A digitally programmable temperature controller is developed based on a phase-locked loop. Temperature under control is converted to frequency form and then compared, in a phase detector, with the reference frequency which corresponds to the target temperature. The detected phase drives the actuator. The frequency difference is also detected by a one-chip microcomputer which changes the reference frequency according to a proportional-integral-derivative operation. A prototype controller achieved 0.1° C stability in the temperature control of a water bath. It is concluded that the principles of control are compatible with intelligent sensors now being developed and are applicable to the control of other quantities, such as humidity, pressure, and flow     

Group routing without group routing tables: an exercise in protocol design

We present a group routing protocol for a network of processes. The task of the protocol is to route data messages to each member of a process group. To this end, a tree of processes is constructed in the network, ensuring that each group member is included in the tree. To build this tree, the group routing protocol relies upon the local unicast routing tables of each process. Thus, group routing is accomplished by composing two protocols: an underlying unicast routing protocol, whose detailed behavior is unknown but its basic properties are given, and a protocol that builds a group tree based upon the unicast routing tables. The group routing protocol is developed in three steps. First, a simple protocol is obtained, and is proven correct. Then, the protocol is refined twice. Each refined protocol improves upon its predecessor by satisfying all of the predecessor's properties plus some additional stronger properties. The final protocol has the property of adapting the group tree to changes in the unicast routing tables without compromising the integrity of the group tree, even in the presence of unicast routing loops.     

Construction on Expansive Soils in Sudan

Expansive soils prevail over a large area of Sudan and have caused significant damages to irrigation systems, water lines, sewer lines, buildings, roads and other structures located on these soils. Damage caused by expansive soils is estimated by the writers to exceed $6,000,000 (8,000,000 Sudanese pounds) annually. The paper summarizes typical damages to show the type, extent and causes of damages and provides information on current design methods being used in Sudan to reduce potential damages. Based on soil surveys and soil properties collected from more than 30 sites, over one‐third of Sudan's 2,600,000?km2 area may have potentially expansive soils. It is recommended that all potential construction sites in the Clay Plain be evaluated for expansive soils.     

Azo disperse dyes for synthetic fibres. 2: Benzimidazole derivatives

Ten variously substituted derivatives ( IIa–j ) of 3′-(benzimidazol-2-yl)-4′-hydroxyazobenzene were prepared. The effects of the nature and orientation of the substituents on the colour and dyeing properties of these dyes on polyester and acrylic fibres were evaluated.     

Effect of Fe on ductility and cavitation in the superplastic Zn-22 Pct Al eutectoid

In this investigation, the ductility and cavitation behavior of five grades of the superplastic Zn-22 pct Al were studied under identical conditions of grain size, temperature, and initial strain rate. These five grades were prepared from high-purity Al and Zn using the same procedure but different Fe impurity levels; grades A, B, C, D, and E contain 1, 40, 120, 400, and 1460 ppm of Fe, respectively. A comparison between the present results and those reported earlier for the creep behavior of the five grades of Zn 22 pct Al demonstrates that while the presence of Fe has no noticeable effect on the steady-state creep rates during deformation in the superplastic region (where maximum ductility occurs), it has a pronounced effect on the ductility and fracture behavior of the alloy. The experimental data show that there is a significant drop in the average elongation to fracture when Fe concentration exceeds 125 ppm, and that the ductility of grade E is approximately 50 pct of grade A for initial strain rates less than 10⁻² s⁻¹. In addition, the data reveal two important findings regarding cavitation behavior. First, neither the initial grain size nor the occurrence of grain growth has an effect on cavitation that is as significant as that arising from the presence of excessive impurities. Second, the presence of other impurities in addition to Fe in Zn-22 pct Al has the effect of enhancing cavitation. The effect of Fe, alone or in the presence of other impurities, on ductility and cavitation in Zn 22 pct Al is examined in terms of phenomena associated with impurity segregation at boundaries. Formerly Research Associate, Materials Section, Department of Mechanical and Aerospace Engineering, University of California, Irvine, CA Formerly Graduate Research Assistant, Materials Science & Engineering, Department of Chemical and Biochemical Engineering, University of California, Irvine, CA This article is based on a presentation made at the “High Temperature Fracture Mechanisms in Advanced Materials” symposium, as a part of the 1994 Fall meeting of TMS, October 2-6, 1994, in Rosemont, Illinois, under the auspices of the ASM/SMD Flow and Fracture Committee.     

Needle track seeding following percutaneous ethanol injection for treatment of hepatocellular carcinoma

We report two cases of needle track seeding in the subcutaneous tissue and intercostal muscles following percutaneous ethanol injection for the treatment of hepatocellular carcinoma. In one patient, tumor seeding was observed 11 months after a total of 12 alcohol injections, and in the other patient, tumor seeding was observed 30 months after a total of 18 alcohol injections. The cases reported in the literature are discussed.     

Iterative solution of the global element equations

A previous paper [4]discussed in detail techniques for setting up the defining equations for the Global Element Method for elliptic partial differential equations, and sketched an iterative method for their solution. For a calculation in two-dimensions using M elements (with a basis of degree N - 1 in each element), operation counts of O(MN⁴) were achieved for both set-up and solution phases. Timings were included demonstrating this count for the set-up, but not the solution, phase. In this paper we describe a modified and simpler version of the iterative solution scheme and report timings obtained with an exploratory implementation of the scheme. These demonstrate the rapid convergence and O(MN⁴) behaviour predicted for it.