Nanoindentation mapping of mechanical properties of cement paste and natural rocks

This paper reports a study to assess nanoindentation mapping of mechanical properties of cement paste and natural rocks. Initial work seems to show that mechanical property mapping by nanoindentation is feasible and can be related to microscopic information. Further work is however required on the effect of indent size and spacing. Such a testing technique can be very useful for materials with different phases to study the intrinsic properties of each component, and also the interaction and properties of the interfacial regions of different phases. The values of Young's modulus and hardness of the individual mineral phases were also determined by statistically analysing a large number of experimental data.     

Support vector regression methodology for prediction of input displacement of adaptive compliant robotic gripper

The prerequisite for new versatile grippers is the capability to locate and perceive protests in their surroundings. It is realized that automated controllers are profoundly nonlinear frameworks, and a faultless numerical model is hard to get, in this way making it troublesome to control utilizing tried and true procedure. Here, a design of an adaptive compliant gripper is presented. This design of the gripper has embedded sensors as part of its structure. The use of embedded sensors in a robot gripper gives the control system the ability to control input displacement of the gripper and to recognize specific shapes of the grasping objects. Since the conventional control strategy is a very challenging task, soft computing based controllers are considered as potential candidates for such an application. In this study, the polynomial and radial basis function (RBF) are applied as the kernel function of Support Vector Regression (SVR) to estimate and predict optimal inputs displacement of the gripper according to experimental tests and shapes of grasping objects. Instead of minimizing the observed training error, SVR _poly and SVR _rbf attempt to minimize the generalization error bound so as to achieve generalized performance. The experimental results show that an improvement in predictive accuracy and capability of generalization can be achieved by the SVR approach compared to other soft computing methodology.     

Alkali-silica reactivity of some frequently used lightweight aggregates

Lightweight aggregates (LWAs) are frequently used in concrete as well as in thermally insulating mortars and grouts, so that information on their alkali-silica reactivity (ASR) is very important. Four LWAs—expanded vermiculite, expanded clay, expanded glass and perlite—were studied regarding their ASR, using the following test methods: the accelerated mortar bar test (ASTM C 1260), the rapid chemical test (ASTM C 289) and the combined scanning electron microscopy-energy dispersive X-ray technique (SEM-EDX). According to these methods, neither the expanded vermiculite nor the expanded clay exhibited any potential ASR. On the other hand, in the case of the aggregates containing a glassy phase (expanded glass and perlite), the results of SEM-EDX analysis showed serious decomposition of aggregate texture due to ASR, although no deleterious expansion was observed in the accelerated mortar bar test. Therefore, suitable test criteria for ASR need to be defined for LWAs of this type when the AMBT method is used, as has already been suggested for slowly reactive aggregates in Australia.     

Variable neighbourhood simulated annealing algorithm for capacitated vehicle routing problems

This article presents the variable neighbourhood simulated annealing (VNSA) algorithm, a variant of the variable neighbourhood search (VNS) combined with simulated annealing (SA), for efficiently solving capacitated vehicle routing problems (CVRPs). In the new algorithm, the deterministic ‘Move or not’ criterion of the original VNS algorithm regarding the incumbent replacement is replaced by an SA probability, and the neighbourhood shifting of the original VNS (from near to far by k← k+1) is replaced by a neighbourhood shaking procedure following a specified rule. The geographical neighbourhood structure is introduced in constructing the neighbourhood structures for the CVRP of the string model. The proposed algorithm is tested against 39 well-known benchmark CVRP instances of different scales (small/middle, large, very large). The results show that the VNSA algorithm outperforms most existing algorithms in terms of computational effectiveness and efficiency, showing good performance in solving large and very large CVRPs.     

Semantic Mediation for Standard-Based B2B Interoperability

The authors discuss a semantic-mediation architecture to advance traditional approaches for standards-based business-to-business (B2B) interoperability. The architecture is supported by the Athena Knowledge Representation and Semantics Mediation tool suite. Initial experimentations with the architecture and the toolset offer discussions of key architectural and functional aspects and suggest directions for future tools enhancements.     

Numerical model of gaseous fuel jet injection into a fluidized furnace

The paper presents a fluid-porous medium model, developed for stationary 2D predictions of fluidized bed. Dense phase is considered a fixed porous medium, while gas–particle interactions and bubbling phase are modeled regarding balance of friction forces between gas and particles. Like referent measurements, predictions of lateral jet injection into the bed suggest the jet penetration length is strongly affected by fluid velocity at the nozzle outlet, while influences of the nozzle vertical position and inclination angle are not significant. Also, the fluid velocity and the nozzle vertical position exert pronounced effects on mixing rate of components (fuel and oxidizer).     

Arterial hypertension in patients on chronic hemodialysis

Arterial hypertension is frequent among chronically dialyzed patients. The kidney obviously plays a major role in arterial blood pressure control. There is a large number of experimental data emphasizing different factors (in addition to renin important in renal hypertension prognosis) such as: sodium balance, angiotensin, etc [1-8]. Sympathetic activity disorders or lack of vasodilatory prostaglandins and quinine may also play a certain role. In uremic patients peripheral arteriolar resistance is increased, unlike normotensive uremic patients or those who prove to be normotensive upon clinical examinations [8, 11-15]. Hypertension occurs in approximately 80% of patients with chronic renal failure, producing a number of complications primarily affecting the CNS and systemic circulation [5-8, 10, 11, 13]. The study concerned patients on chronic dialysis, with a male to female ratio of 69.9%:32.1%. In most of them the underlying disease, which caused chronic renal failure, was glomerulonephritis (60.0%), then pyelonephritis (17.0%) and nephrosclerosis, nephrolithiasis, polycystic kidney and, finally, renal tumours. The effect of permanent haemodialysis during the first year of treatment, was efficacious on hypertension in 1704 (65.1%) patients; in 672 (25.7%) patients therapeutical effects were achieved by dialysis and antihypertensive drugs, while in 240 (9.2%) subjects there was no improvement. General observations suggest that two types of arterial hypertension persisted in patients with chronic renal failure: volume-dependent arterial hypertension which is more frequent (90-95%) among haemodialyzed patients and renin-dependent hypertension. Such findings are of utmost importance indicating that hypervolaemia is one of the major factors in the development of arterial hypertension in patients with chronic renal failure, with renin playing the secondary role. Salt-free diet should be used in the treatment of arterial hypertension for years, a well conducted haemodialysis is highly effective in the control of arterial hypertension among these patients. In our series of patients dialysed three times a week; normalization of blood pressure was faster with lower incidence of hypertensive crises during haemodialysis and with few complications. Water and sodium excess was reduced by frequent haemodialyses and sudden changes in electrolyte, hydrostatic and other metabolic effects were minimized. Increased values of plasma renin activity were observed in a small number of patients. Ultrafiltration is insufficient for normalization of blood pressure. Hypertensive crises were frequent in these patients. Their response to medicaments such as methyldopa, beta-adrenergic blockers or other antihypertensive drugs, was good. Severe changes in blood vessels, especially in fundus oculi blood vessels were frequent in these patients. The life of hypertensive glomerulonephritis patients was especially endangered (graphs 1-6). In addition to the mentioned factors arterial hypertension during haemodialysis may also be of cardiac origin, including increase in cardiac output due to arteriovenous anastomosis, disequilibrium syndrome, changes in osmotic gradient of both extra- and intracellular spaces with resultant arteriolar wall oedema, erythrocyte amount, hypoxia, composition of dialysis fluid (sodium concentration), plasma osmotic pressure, metabolic acidosis and other factors. More recently, natriuretic hormone has also been indentified as a cause of vascular refraction. Peripherial arteriolar resistance as a cause of arterial hypertension among uremic patients must not be forgotten, because the genesis of arterial hypertension in patients with chronic renal failure is multifactorial. The highest percentage refers to volume-dependent arterial hypertension, whereas the percentage of other aetiologic factors is lower. Haemodialysis enables the normalization of blood pressure in most of hypertensive patients.