A knowledge-based search framework for designing composite structures

In this paper, a search framework is presented that makes a genetic algorithm (GA) a practical engineering tool for searching discrete and nonconvex design spaces. It is shown that near optimal designs can be relatively quickly found if three problems are addressed: (i) the dimensionality of a design space is reasonably reduced, (ii) fast function evaluations are available, and (iii) genetic operators are tailored to the application at hand. In our work, the number of active design variables is reduced by using a rule-based fuzzy logic inference engine to process knowledge about the structure's behaviour. The use of a parallel computing environment for structural analysis in conjunction with data retrieval from binary-like trees effectively reduces the time required to perform genetic searching. Three different selection operators along with a permutation-like operator for the reduced problem are evaluated for their effectiveness in locating the global optimum. As an example, the stacking sequence for maximizing a buckling load for a stiffened square panel with a circular cut-out and subject to thermal and shear loading is designed.     

Synthesis of Novel Pyrido[1,2-c]pyrimidine Derivatives with 6-Fluoro-3-(4-piperidynyl)-1,2-benzisoxazole Moiety as Potential SSRI and 5-HT1A Receptor Ligands

Two series of novel 4-aryl-2H-pyrido[1,2-c]pyrimidine (6a–i) and 4-aryl-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine (7a–i) derivatives were synthesized. The chemical structures of the new compounds were confirmed by ¹H and ¹³C NMR spectroscopy and ESI-HRMS spectrometry. The affinities of all compounds for the 5-HT_1A receptor and serotonin transporter protein (SERT) were determined by in vitro radioligand binding assays. The test compounds demonstrated very high binding affinities for the 5-HT_1A receptor of all derivatives in the series (6a–i and 7a–i) and generally low binding affinities for the SERT protein, with the exception of compounds 6a and 7g. Extended affinity tests for the receptors D₂, 5-HT_2A, 5-HT₆ and 5-HT₇ were conducted with regard to selected compounds (6a, 7g, 6d and 7i). All four compounds demonstrated very high affinities for the D₂ and 5-HT_2A receptors. Compounds 6a and 7g also had high affinities for 5-HT₇, while 6d and 7i held moderate affinities for this receptor. Compounds 6a and 7g were also tested in vivo to identify their functional activity profiles with regard to the 5-HT_1A receptor, with 6a demonstrating the activity profile of a presynaptic agonist. Metabolic stability tests were also conducted for 6a and 6d.     

Proteinous amino acids in muscle cytosol of rats' heart after exercise and hypoxia

Levels of 19 proteinous amino acids and of total free amino acids were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular heart muscle cardiomyocytes. These amino acids were assayed after the rats had been exposed to either exercise (swimming) or hypoxia (hypobaric pressure of 686 hectoPascals). Out of the total free amino acids levels of arginine, glutamine and cysteine in atrial and ventricular cardiac muscle cytosols of control rats were the highest of all amino acids assayed. The control levels of all other amino acids assayed in atrial or ventricular cardiac muscles ranged from 0.1% to 10.6% of the total free amino acids in the control rats. Physical stress (exercise and hypoxia) significantly reduced the total amount of cytosolic free amino acids in both heart muscles. While hypoxia decreased the levels of arginine in both heart muscles, exercise abolished the level of cysteine in the atrial heart muscle. Decrease in arginine levels, and elimination of cysteine from the heart's atrial muscle after physical stress, may be attributed to its utilization of nitric oxide and to its synthesis of atriopeptin and/or endothelin during stress. No change was recorded in either experimental group in the level of glutamine in heart muscle cytosol. Exercise and hypoxia affect, in different modes, the levels of all other amino acids assayed, except for tryptophan, tyrosine, and histidine, which are precursors of endogenous neurotransmitters. The impact of proteinous amino acids on some bodily functions is discussed.     

加料流率对SFBR工艺去除营养物的影响

采用序半连续式反应器在不同的加料流率下,对人工合成废水营养物的去除进行了研究.氮化合物的去除是在一个操作循环中采用顺序进行硝化和反硝化反应,加料流率分别为0.05,0.10,0.15 L/h 3个不同的水平,不同的加料流率对COD,氮化合物(NH4-N和NO3-N)去除和微生物生长的影响进行了研究.结果表明,加料流率对COD、氮化合物(NH4-N和NO3-N)去除和微生物生长的都有一定的影响.当加料流率为0.05 L/h时,COD有最高去除率(84%)、最高的总氮去除率(64%),微生物的生长速率没有明显的影响.并利用一组涉及到多个微生物反应的动力学数学模型,分析了加料流率对同时去除碳、氮化合物率和微生物生长的影响.     

Influence of COD/N Ratios on Simultaneous Removal of C and N Compounds in Biological Wastewater Treatment in Sequencing Fed-Batch Reactor and Kinetic Analysis

The impact of chemical oxygen demand/nitrogen (COD/N) values of feed wastewater on COD and nitrogen removal and biomass growth in a sequencing fed-batch reactor (SFBR) operation was investigated. The multiple microbial reactions involved in the simultaneous removal process of carbonaceous and nitrogenous components in the SFBR system were analyzed using a set of kinetics mathematical model. The results indicate that COD/N ratios strongly influence COD and total nitrogen removal efficiency. The COD removal efficiency per gram microorganism changed from 64.3 to 78.1% at COD/N = 11.9–2.5. The total nitrogen removal efficiency changed from 10.3 to 34.2% at COD/N = 2.5–11.9. However, variable COD/N ratios of feed wastewater are not marked for biomass growth rate.     

Remote automated multi-generational growth and observation of an animal in low Earth orbit

The ultimate survival of humanity is dependent upon colonization of other planetary bodies. Key challenges to such habitation are (patho)physiologic changes induced by known, and unknown, factors associated with long-duration and distance space exploration. However, we currently lack biological models for detecting and studying these changes. Here, we use a remote automated culture system to successfully grow an animal in low Earth orbit for six months. Our observations, over 12 generations, demonstrate that the multi-cellular soil worm Caenorhabditis elegans develops from egg to adulthood and produces progeny with identical timings in space as on the Earth. Additionally, these animals display normal rates of movement when fully fed, comparable declines in movement when starved, and appropriate growth arrest upon starvation and recovery upon re-feeding. These observations establish C. elegans as a biological model that can be used to detect changes in animal growth, development, reproduction and behaviour in response to environmental conditions during long-duration spaceflight. This experimental system is ready to be incorporated on future, unmanned interplanetary missions and could be used to study cost-effectively the effects of such missions on these biological processes and the efficacy of new life support systems and radiation shielding technologies.     

High-temperature air and steam gasification of densified biofuels

An experimental study was carried out to investigate gasification of densified biofuels using highly preheated air and steam as a gasifying agent. Preheat of air and steam is realised by means of the newly developed high-cycle regenerative air/steam preheater. Use of highly preheated feed gas provides additional energy into the gasification process, which enhances the thermal decomposition of the gasified solids. For the same type of feedstock the operating parameters, temperature, composition and amount of gasifying agent, were varied over a wide range. Results of experiments conducted in a high-temperature air/steam fixed bed updraft gasifier show the capability of this technology of maximising the gaseous product yield as a result of the high heating rates involved, and the efficient tar reduction. Increase of the feed gas temperature reduces production of tars, soot and char residue as well as increases heating value of the dry fuel gas produced. Overall, it has been seen that the yield and the lower heating value of the dry fuel gas increase with increasing temperature.     

Hot explosive compaction of aluminum-nickelide composites

Two series of nickel-coated aluminum (Al-Ni) powder compositions were consolidated to full or near-full density by a hot-explosive-compaction (HEC) technique. Mixtures of 78Al-22Ni at. pct (63Al-37Ni wt pct) or 39Al-61Ni at. pct (23Al-77Ni wt pct) were placed in cylindrical containers, preheated to a range of temperatures from ambient to 1000 °C, and once at a uniform temperature, explosively compacted into a 150-mm-long and 15-mm-diameter rod-shaped billet using a cylindrical detonation arrangement. The resultant billets were sectioned and prepared for examination by optical microscopy and scanning electron microscopy (SEM). Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and microhardness measurements were used to characterize the billet morphology, structure, and chemical composition. Analysis revealed that depending on the preheating temperature, the initial Al-Ni composition transformed into several aluminum nickelide (Al-Ni) intermetallics. The onset and nature of the shock-induced transformation from the precursors into the products are discussed.     

Thermal Properties of Raw Hemp Fiber as a Loose-Fill Insulation Material

The article presents the possibilities of using hemp fiber as a loose-fill insulation material. The article presents the results of research concerning raw hemp fiber obtained from the Polish crop of industrial hemp of Bia?obrzeskie variety. The analysis involved evaluation of thermal conductivity in function of bulk density and air permeability, the properties important for insulation materials. The results of laboratory investigation were used to create the numerical simulation models of heat transfer in the frame wall partitions filled with hemp fibers. The study showed that with the increase of bulk density, the thermal conductivity and air permeability of material decrease. The obtained lambda values are comparable with the characteristic values for conventional thermal insulation materials. The results of heat transfer and temperature distribution reveal that hemp fibers characterize with strongly air permeance, what affects on the need for additional barriers against air filtration.     

A hybrid numerical/neurocomputing strategy for sensitivity analysis of nonlinear structures

A hybrid numerical/neurocomputing (HN/N) strategy is presented for the evaluation of selective sensitivity coefficients of nonlinear structures. In the hybrid strategy, multilayer feedforward neural networks are used to extend a range of the validity of predictions of sensitivity coefficients made by Padé approximants. To further increase the accuracy and the range of network predictions, a data expansion strategy is used in which additional training data are generated by using extrapolated values of the coefficients in a Taylor series. Within this strategy a number of techniques are examined for evaluating derivatives of response functions. The effectiveness of the HN/N strategy is assessed by performing numerical experiments for composite panels subjected to combined thermal and mechanical loads. It is shown that the HN/N strategy reduces the number of full-system analyses and allows obtaining selective information about the structural response and the sensitivity coefficients.