Improvement in performance of cryocoolers as condensers

Modifications to the cold head of a Cryomech PT410 pulse tube cryocooler, being used as a helium condenser, have led to an increase in liquefaction rate from 12.8 to 21.4 L/day. These modifications are the first experimental results from attempts to enhance the use of natural convective heat transfer to precool the helium vapour prior to liquefaction.     

Rare earth organic complexes as down-shifters to improve Si-based solar cell efficiency

This work reports on the optical and electrical characterization of crystalline silicon based solar modules encapsulated with ethylene-vinyl-acetate layers (that is the encapsulating matrix used nowadays by the photovoltaic industry) doped with a single europium complex whose sensitized region is broadened due to the presence of a co-ligand. Such europium doped EVA layers are able to realize down-shifting of photons with wavelength lower than 460 nm without introducing modifications of the industrial process leading to the fabrication of the photovoltaic modules. This effect has been proven under Air Mass 1.5 conditions (simulating terrestrial applications), where a 2.9% relative increase of the total power delivered by the encapsulated modules has been observed, allowing a reduction in the watt-peak price.     

Loopy MSC: a simple way to improve multiplicative scatter correction

Multiplicative scatter correction (MSC) is a widely used normalization technique. It aims to correct spectra in such a way that they are as close as possible to a reference spectrum, generally the mean of the data set, by changing the scale and the offset of the spectra. When there are other differences in the spectra than just a scale and an offset, the mean spectrum changes after MSC. As a result, another MSC, with the new mean spectrum as the reference, will result in an additional correction. This paper studies the effect of multiple applications of MSC.     

Configuration to improve second-harmonic-generation conversion efficiency

The dependence of second-harmonic-generation (SHG) conversion efficiency on the intercrystal phase shift between two nonlinear crystals is analyzed with heuristic theory, and a novel scheme for SHG with two cascaded nonlinear crystals and a polarization modulator is proposed. More than 30 W output power is obtained experimentally at 532 nm with 70% external doubling efficiency. To the best of our knowledge, this is the highest conversion efficiency obtained with LiB3O5 crystal external frequency doubling. This scheme provides a simple and effective method for improving second-harmonic conversion efficiency.     

Environmentally-friendly mortars: a way to improve bond between mortar and brick

In order to find new application fields for either fine materials coming from building demolition or industrial byproducts, some mortars, in which fine recycled materials, obtained from a plant where rubble from building demolition are ground, are substituted to natural sand, were tested.Moreover, mortars containing either fly ash or ground brick powder as partial cement replacement were studied.Based on characterization results and performance evaluations, recycled-aggregate mortar seems to be superior in terms of mortar-brick bond strength, mainly because of its rheological properties.In addition, the use of fine recycled aggregate instead of natural sand is in accordance with the sustainable development concept, with recycling and reuse of building rubble playing a key role in meeting the need to complete the building life cycle.     

一种提高平稳随机载荷识别精度的方法

针对动态随机载荷识别结果在固有频率附近因传递函数矩阵病态而出现载荷识别误差较大的问题,在逆虚拟激励法的基础上提出一种条件数加权平均算法尝试改善识别的精度。方法用仿真和试验验证了对识别精度的改善效果。同时采用频响函数条件数的大小来作为判断识别结果可靠度和测点组合选择的一个参考,减少了工作量并取得了良好的识别效果。提出了一些实际操作中的建议,为工程实际提供参考。     

Laser sintering of coated polyamide 12: a new way to improve flammability

Journal of Materials Science - In this study coatings of kaolin and talc particles were successfully applied on the surface of polyamide 12 powder intended for laser sintering (LS). Microscopic...     

如何提升建筑施工企业审核的有效性

审核有效性,简单表述就是:"完成策划活动和达到策划结果的程度."审核方案策划在整个审核活动中的重要作用,是体现审核有效性的前提和基础.     

Exploring ways to improve efficiency of gasdynamic energy separation

This work is devoted to research into ways to improve the efficiency of gasdynamic energy separation in the pipe Leontiev. It is shown that restoring the coefficient of temperature r depending on the Prandtl number Pr has the greatest impact on the magnitude of energy separation. The conducted analysis showed that for a gas with Pr = 0.7 the most promising ways to improve the efficiency of gasdynamic energy separation are the partial condensation of the working body and the use of regular relief that is deposited onto the wall of the supersonic channel in the pipe Leontiev. We have performed a modification of the calculation method and its verification using experimental data obtained on natural gas. The results of numerical modeling have shown that the use of regular relief (dimples) in this class of devices is effective.     

Employee substitutability as a tool to improve the robustness in personnel scheduling

OR Spectrum - Organisations usually construct personnel rosters under the assumption of a deterministic operating environment. In the short term, however, organisations operate in a stochastic...     

Ellipsoidal and parabolic glass capillaries as condensers for x-ray microscopes

Single-bounce ellipsoidal and paraboloidal glass capillary focusing optics have been fabricated for use as condenser lenses for both synchrotron and tabletop x-ray microscopes in the x-ray energy range of 2.5-18 keV. The condenser numerical apertures (NAs) of these devices are designed to match the NA of x-ray zone plate objectives, which gives them a great advantage over zone plate condensers in laboratory microscopes. The fabricated condensers have slope errors as low as 20 murad rms. These capillaries provide a uniform hollow-cone illumination with almost full focusing efficiency, which is much higher than what is available with zone plate condensers. Sub-50 nm resolution at 8 keV x-ray energy was achieved by utilizing this high-efficiency condenser in a laboratory microscope based on a rotating anode generator.     

Separation efficiency of particle-packed HPLC microchips

We report an experimental study of separation efficiency in microchip high-performance liquid chromatography (HPLC). For this study, prototype HPLC microchips were developed that are characterized by minimal dead volume, a separation channel with trapezoidal cross section, and on-chip UV detection. A custom-built stainless steel holder enabled microchip packing under pressures of up to 400 bar and ultrasonication. Bed densities were investigated with respect to the packing conditions and consistently related to pressure drop over the packed microchannels and separation efficiency under isocratic elution conditions. The derived plate height curves show a decrease of mobile phase mass transfer resistance with increasing bed density. High bed densities are critical to separation performance in noncylindrical packed beds, because only at low bed porosities does hydrodynamic dispersion in noncylindrical packings come close to that of cylindrical packings. At higher bed porosities, the presence of fluid channels of advanced flow velocity in the corners of noncylindrical packings affects hydrodynamic dispersion strongly. We demonstrate that the separation channels of HPLC microchips can be packed as densely as the cylindrical fused-silica capillaries used in nano-HPLC and that consequently microchip-HPLC separation efficiencies comparable to those of nano-HPLC can be achieved.     

Chaotic pulse position modulation to improve the efficiency of sonar sensors

Ultrasonic devices are widely used in robotics as exteroceptive sensors for ranging measurements. Robotic applications often involve a large number of sonars operating concurrently, giving rise to the phenomenon of crosstalk. In this work, the problem of improving performance of ultrasonic devices in the presence of crosstalk and noise is addressed. In order for each device to discriminate its own echo, chaos is exploited to create unique firing sequences. In particular, the firing scheme described in this work is inspired to a modulation scheme used in chaotic communications, called chaotic pulse position modulation (CPPM). The evaluation of the time of flight is performed by a detection filter. The experimental setup consists of a Polaroid 600 electrostatic transducer driven by a continuous CPPM modulator. Experimental results confirm the suitability of the approach.     

Potential method to improve the treatment efficiency of persistent contaminants in industrial wastewater

The objective of this work was to evaluate a potential method for improving the treatment efficiency of persistent contaminants in industrial wastewater. Adsorption with powdered activated carbon (PAC) was applied as pre-treatment and operational conditions as pH, temperature, carbon concentration and time were investigated in laboratory scale for different streams generated in a fine chemical industry. Chemical oxygen demand (COD) removal efficiencies of 63 and 50% were attained for two important industrial streams, Product C after acid treatment and precipitation and Influent, at pH 7, room temperature and with 5 and 15 g l(-1) of PAC, respectively. Biodegradation assays showed that PAC adsorption enhanced COD removal efficiency. PAC pre-treatment increased the COD removal of Product C after production stream from 15 to 80% and improved the biodegradability of the Influent stream by 50%.     

Co-processing as a tool to improve aqueous dispersibility of cellulose ethers

Cellulose ethers are important materials with numerous applications in pharmaceutical industry. They are widely employed as stabilizers and viscosity enhancers for dispersed systems, binders in granulation process and as film formers for tablets. These polymers, however, exhibit challenge during preparation of their aqueous dispersions. Rapid hydration of their surfaces causes formation of a gel that prevents water from reaching the inner core of the particle. Moreover, the surfaces of these particles become sticky, thus leading to agglomeration, eventually reducing their dispersion kinetics. Numerous procedures have been tested to improve dispersibility of cellulose ethers. These include the use of cross-linking agents, alteration in the synthesis process, adjustment of water content of cellulose ether, modification by attaching hydrophobic substituents and co-processing using various excipients. Among these, co-processing has provided the most encouraging results. This review focuses on the molecular mechanisms responsible for the poor dispersibility of cellulose ethers and the role of co-processing technologies in overcoming the challenge. An attempt has been made to highlight various co-processing techniques and specific role of excipients used for co-processing.     

Application of cleaner technologies in milk processing industry to improve the environmental efficiency

Changes in production processes and products that result in improvement of environmental, economic and social performance of enterprises are an important element of the overall process towards more sustainable production. The aim of this article is to demonstrate the application of cleaner production and eco-design as sustainable production tools to improve the environmental efficiency of milk processing industry. Milk processing industry is one of the largest and dynamically developing branches of industry in the world. The main impact of milk processing industry on the environment is related to energy and water consumption, and waste and wastewater generation. A number of potential solutions to improve the environmental performance of milk processing industry, to reduce energy and resources consumption are analysed: substitution of cleaning agent in the milk receiving bar for washing of milk tankers with the specialised acidic detergent, integration of the automated CIP washing system in the butter bar, implementation of water recycling system to collect warm (35?°C) water, integration of the membrane technologies for the evaporation process and the use of filtrate received during the condensation for steam generation in the boiler house. Finally, an eco-design solution for cans of milk products is presented. All these proposals have been implemented in the milk processing company.     

Natural gas partial oxidation process as a way to synthesize onion-like carbon

Abstract

Onion-like carbon (OLC) particles were produced as a byproduct of thermal partial oxidation of methane under different O₂/Natural Gas (NG) ratio. It was established that the particles have quasi-spherical morphology and concentric shell structure. The particles have an outer diameter of 20–60?nm while the inner cage is rather typical for onions and has a diameter below 1?nm. The concentric graphitic structure and spherical symmetry along with the absence of amorphous carbon were confirmed by transmission electron microscopy, electron diffraction, EDX spectroscopy and Raman investigation. Variation of O₂/NG ratio was proved a powerful tool for controlling OLC particles yield and structure. The formation of single-core or multicore OLC can be controlled by thermal partial oxidation process.