Entropy generation for forced convection in a porous saturated circular tube with uniform wall temperature

A numerical study is reported to investigate both the First and the Second Law of Thermodynamics for thermally developing forced convection in a circular tube filled by a saturated porous medium, with uniform wall temperature, and with the effects of viscous dissipation included. A theoretical analysis is also presented to study the problem for the asymptotic region applying the perturbation solution of the Brinkman momentum equation reported by Hooman and Kani [1]. Expressions are reported for the temperature profile, the Nusselt number, the Bejan number, and the dimensionless entropy generation rate in the asymptotic region. Numerical results are found to be in good agreement with theoretical counterparts

Entropy generation analysis of thermally developing forced convection in fluid-saturated porous medium

Entropy generation for thermally developing forced convection in a porous medium bounded by two isothermal parallel plates is investigated analytically on the basis of the Darcy flow model where the viscous dissipation effects had also been taken into account. A parametric study showed that decreasing the group parameter and the Péclet number increases the entropy generation while for the Brinkman number the converse is true. Heatline visualization technique is applied with an emphasis on B

Population dynamics of pearl oyster Pinctada radiata west of Lavan Island of the Persian Gulf, Iran

Investigation on pearl oyster, Pinctada radiata growth and mortality parameters was carried out from September 2001 to October 2002 in west of Lavan Island using scuba diving method. Hinge length (HL) and dorsoventral measurement (DVM) relationship was significantly (r ^ (2) =0.98) linear. Weight and dorsoventral measurement relationship was shown to be W=0.0004 L ^ (2.812) (r ^ (2) =0.98). Asymptotic length (L infinity) and growth rate (K) were estimated at 98 (mm) and 0.96 y ^ (-1) respectively. More than 70 percent of the individuals were matured in April 2001. Mortality parameters including natural mortality (M), total mortality (Z) and fishery mortality (F) were estimated to be 1.21y ^ (-1), 1.68y ^ (-1) and 0.66y ^ (-1) respectively. Exploitation rate was estimated to be 0.27 in this survey

PUFA content of silages prepared from tuna cannery wastes

Ensiling as one of the best methods for utilization of tuna wastes was investigated. docosahexaenoic acid [DHA C22:6(n-3)]- rich products were obtained from the wastes (viscera and dark meat) of four tuna species, namely longtail, skipjack, yellowfin and kawakawa by a procedure involving ensiling in organic acids followed by neutralization. Identification of fatty acids in the samples was performed by comparison with chromatograms of fatty acids standard. Total lipid content of silages varied from 10.41% in skipjack dark meat silage to 22.01% in kawakawa viscera silage, but all lipids contained high percentages of DHA and EPA [eicosapanteoneic acid C20:5(n-3)]. The highest DHA ratio (15% of total lipids) was found in the lipid of skipjack viscera silage and the highest ratio of EPA (11% of total lipids) belonged to the lipids of kawakawa dark meat silage. ANOVA test results indicated that DHA ratio was significantly high before silage preparation and linolenic acid [C18:3(n-3)] content significantly differed between the species (p<0.05)

Effect of cognitive-behavioral training on pain self-efficacy, self-discovery, and perception in patients with chronic low-back pain: A quasi-experimental study

Background: Correcting false cognitionsandestablishing preventivebehaviors in patients with chroniclow-back pain can improve self-efficacy and self-discovery of these patients against the physical and psychological consequences of chronic back pain through reinforcing thoughts and constructive behaviors. Objectives: This study aimed to investigate the effectiveness of cognitive-behavioral training in self-efficacy, self-discovery, and pain perception of patients with chronic low-back pain. Methods: Based on a quasi-experimental design, 40 patients with chronic low-back were selected through purposive sampling and assigned into two groups of intervention (n = 20) and control (n = 20). After administering the pain self-efficacy (PSE) scale, the self-discovery scale (SDS), and the pain perception questionnaire (MPQ) to both groups, the intervention group received the cognitive-behavioral training while the control group did not receive the intervention. The post-test was performed on both groups and the data were analyzed using SPSS. Results: The scores of pain self-efficacy and self-discovery (self-awareness and acceptance, commitment and attraction, transcendence and development, and personal growth) were higher in the intervention group than in the control group (P < 0.01). The highest increase with an effect size of 0.514 was related to the self-awareness and acceptance subscale. In addition, the pain assessment perception was the only reduced subscale among the other dimensions of pain perception (P < 0.01). Conclusions: Psychosocial complementary therapies can provide patients suffering from chronic pain with better physical and mental conditions to have a higher quality of life. © 2019, Author(s)

Comments on “Flow, thermal, and entropy generation characteristics inside a porous channel with viscous dissipation” by S. Mahmud and R.A. Fraser [Int. J. Thermal Sciences 44 (2005) 21–32]

Hoomen, Merrikh and Ejlali presents comment on the paper on 'Flow, thermal, and entropy generation characteristics inside a porous channel with viscous dissipation' by S. Mahmud and R.A. Fraser. The paper presents closed form solutions to the velocity and temperature distributions that would be very useful for checking numerical computations. The authors have applied the fluid thermal conductivity kf in all of the equations, that should be replaced by the effective thermal conductivity. They have presented the temperature distribution and the Nusselt number as a function of the Darcy number only, inspite of the fact that Re, Pr, and Ec will affect the temperature profile. The authors have applied a clear-fluid compatible term in the entropy production term that has not been already considered in the thermal energy equation. The reliability of the numerical results is questionable though the authors have applied a previously tested numerical scheme

A Survey of Fault-Tolerance Techniques for Embedded Systems from the Perspective of Power, Energy, and Thermal Issues

The relentless technology scaling has provided a significant increase in processor performance, but on the other hand, it has led to adverse impacts on system reliability. In particular, technology scaling increases the processor susceptibility to radiation-induced transient faults. Moreover, technology scaling with the discontinuation of Dennard scaling increases the power densities, thereby temperatures, on the chip. High temperature, in turn, accelerates transistor aging mechanisms, which may ultimately lead to permanent faults on the chip. To assure a reliable system operation, despite these potential reliability concerns, fault-tolerance techniques have emerged. Specifically, fault-tolerance techniques employ some kind of redundancies to satisfy specific reliability requirements. However, the integration of fault-tolerance techniques into real-time embedded systems complicates preserving timing constraints. As a remedy, many task mapping/scheduling policies have been proposed to consider the integration of fault-tolerance techniques and enforce both timing and reliability guarantees for real-time embedded systems. More advanced techniques aim additionally at minimizing power and energy while at the same time satisfying timing and reliability constraints. Recently, some scheduling techniques have started to tackle a new challenge, which is the temperature increase induced by employing fault-tolerance techniques. These emerging techniques aim at satisfying temperature constraints besides timing and reliability constraints. This paper provides an in-depth survey of the emerging research efforts that exploit fault-tolerance techniques while considering timing, power/energy, and temperature from the real-time embedded systems’ design perspective. In particular, the task mapping/scheduling policies for fault-tolerance real-time embedded systems are reviewed and classified according to their considered goals and constraints. Moreover, the employed fault-tolerance techniques, application models, and hardware models are considered as additional dimensions of the presented classification. Lastly, this survey gives deep insights into the main achievements and shortcomings of the existing approaches and highlights the most promising ones

Hydrodynamic modeling of traffic jams in intracellular transport in axons

Irregularities in intracellular traffic in axons caused by mutations of molecular motors may lead to “traffic jams”, which often result in swelling of axons causing such neurodegenerative diseases as Alzheimer’s disease and Down syndrome. Hence, it is of particular interest to mathematically model the formation of traffic jams in axons. This paper adopts the hydrodynamic continuity equations for intracellular transport of organelles as developed by Smith and Simmons [1] whereas the Kerner and Konhäuser [2] model for traffic jams in highway traffic is applied to predict the velocity field. It is observed that combination of the two sets of equations can comprehensively predict the traffic jams in axons without the need to any additional assumption or modification