Energy saving in agricultural buildings through fan motor control by variable frequency drives

A comparison was conducted between ON–OFF and variable frequency drive (VFD) systems to control ventilation fans of greenhouses and poultry houses. The study aimed to determine the effect of each system on the energy consumption and resulting microclimate within the houses. The experiments were carried out in a commercial-size greenhouse in which pepper was grown and in commercial poultry houses. Reducing the fan speed with the VFD system resulted in reductions in the airflow rate through the houses and energy consumption, the latter being much more significant. The study showed that VFD control can reduce electricity consumption compared with ON–OFF operation. In the present study, the average energy consumption with the VFD control system was about 0.64 and 0.75 of that with an ON–OFF system in the greenhouse and poultry houses, respectively. The average greenhouse daily air temperatures and humidity ratios obtained with each control system between 07:00 and 18:00 were nearly equal. The results obtained in the greenhouse further showed that the VFD system has a greater potential than the ON–OFF, to reduce the range of amplitude variations in the air temperature and humidity ratio within the greenhouse. The average air temperatures over day and night, in the poultry houses, with each control system were nearly equal. The relative humidity, however, was slightly lower with VFD than with ON–OFF. Reductions in the range of amplitude variations of the air temperature and humidity were also observed in the poultry houses.     

Thermite powder ignition by localized microwaves

This paper presents a new method to ignite pure thermite powder by low-power microwaves (～100 W). In this method, the microwave energy is supplied locally to the powder. It creates a confined hotspot, and initiates a self-propagating combustion in the entire powder volume. The coupled thermal–electromagnetic interaction evolved within the powder prior to its ignition is simulated theoretically, taking into account the powder’s temperature-dependent parameters. The simulation results show a thermal-runaway instability and localized heating within a confined hotspot, induced mostly by the microwave’s electric-field component. The experimental setup employs accordingly an open-end applicator implemented by a miniature solid-state microwave-drill device inserted into the thermite powder as a local igniter. The experimental results show ignition within ～3 s at 2.1-GHz, 100-W microwave injection, in agreement with the theoretical model. The dependence of the minimal microwave power on the exposure time required to reach combustion is identified. Practical aspects and potential applications of this mechanism, such as rust conversion, energy production, and propulsion are indicated.     

The Vanpool Assignment Problem: Optimization models and solution algorithms

We present optimization models and solution algorithms for the Vanpool Assignment Problem. A vanpool is typically a group of 9-15 passengers who share their commute to a common target location (typically an office building or corporate campus). Commuters in a vanpool drive from their homes to a park-and-ride location where they board a van and ride together to the target location; at the end of the work day they ride together back to the park-and-ride location. The Minimum Cost Vanpool Assignment Model (MCVAM) developed in this study is motivated by a program offered by Gulfstream Aerospace, a large employer in the Dallas/Fort-Worth area, Dallas Area Rapid Transit (DART), and Enterprise Rent-A-Car. Our MCVAM imposes constraints on the capacity of each van and quality-of-service constraints on the cost and travel time involved in joining a vanpool. The goal of the MCVAM is to minimize the total cost of a one-way trip to the target location for all employees (including those employees who opt-out of the program and choose not to join a vanpool). To the best of our knowledge, this is the first mathematical programming model proposed for the standard (one-stop) Vanpool Assignment Problem. The MCVAM models the current practice in vanpooling of using one park-and-ride location per vanpool. We also present a Two-Stop MCVAM (TSMCVAM) that offers significant cost savings compared to the MCVAM with little or no increase in trip times for most passengers by allowing vanpools to stop at a second park-and-ride location. We present heuristics for the TSMCVAM which are shown in a computational study to find solutions with optimality gaps ranging from 5% to 10% in CPU times ranging from 1 to 15 min for problem instances with up to 600 employees and 120 potential park-and-ride locations.     

高纯度番茄红素的制备

番茄酱需要经过预处理后才能用于制备高纯度的番茄红素。该文详细考察了预处理各因素对番茄红素提取率和纯度的影响,确定了制备高纯度番茄红素的最优工艺为:取100 g番茄酱,加入200 mLc(Na2CO3)=0.5mol/L的水溶液于40℃皂化30 m in,然后用稀硫酸将皂化液中和起泡至pH=4~5。离心分离,得到的固体部分用100 mLw(C2H5OH)=95%的乙醇处理10 m in后,用有机溶剂进行提取。提取液在低温下结晶,制得的番茄红素质量分数达到了95%,整个过程的提取率为79%。     

Interaction of proteins with ultrafiltration membranes: Development of a nonfouling index test

Ultrafiltration membranes were prepared from homopolymer [polyacrylonitrile (PAN), polyethersulfone (PES), and polyvivylidenefluoride (PVDF)] and acrylonitrile copolymers with increasing acrylamide content. The membranes containing acrylamide were more hydrophilic and had a smaller dispersive surface energy than those prepared from the acrylonitrile homopolymer. A new nonfouling index (NFI) test was devised and appears to distinguish well between ultrafiltration membranes of different hydrophilicity–hydrophobicity balance. The NFI indices of acrylamide containing copolymer membranes were much higher than those of membranes cast with commercial membrane materials such as PAN, PES, and PVDF. The NFI of ultrafiltration membranes increased as acrylamide substitution in the copolymer increased. The use of acrylamide containing copolymers substantially eliminated intrinsic fouling. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1600–1606, 2000     

Coating metal oxide particles via the combustion of deposited polymer precursors

Water-swellable chelated polymers were synthesized, starting either from (1) In(III) or In(III) and Sn(II) as central ions and N-trimethoxysilylpropylethylenediamine or ethylenediamine each together with ethylenediaminetetraacetic acid (EDTA) as coordination ligands, or from (2) Ag(I) as the central ion and ethylene glycol (EG) and EDTA as coordination ligands, as follows: The nitrate(s) of the above metal ions together with the corresponding ligands were dissolved in water, and the solution was concentrated by heating to carry out the chelating polymerization. After cooling, the polymer was dried and ground to a fine powder, which was then mixed with a metal oxide powder by grinding in the presence of a small amount of water. A paste was thus obtained, which, after drying, was calcined at 200°C and subsequently at 750°C. The polymer became a sticky gel at 200°C, which adhered to the surface of the metal oxide particles; it was converted to an inorganic coating, In₂O₃—SnO₂—SiO₂, In₂O₃—SnO₂, SnO₂, or Ag, during the subsequent calcination at 750°C. Two metal oxide powders, namely, the electrically conductive In₂O₃ and the nonconductive SnO₂, were used as substrates. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) indicated that the substrate particles were coated after calcination by a multicomponent oxide or silver layer. Temperature-resistant electrically antistatic film could be prepared by using the metal oxide coated In₂O₃ particles as pigments and polypropylsiloxane as the binder. The Ag-coated SnO₂ powder had a conductivity σ = 1.0 × 10⁻³ S cm⁻¹ at 8.6 vol % Ag, while the mechanically mixed powders of Ag and SnO₂ exhibited a conductivity of 2.0 × 10⁻⁷ S cm⁻¹ at 16 vol %. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1891–1903, 1998     

Flexible polyurethane foam. II. Fire retardation by tris(1,3-dichloro-2-propyl) phosphate. Part B. Examination of the condensed phase (the pyrolysis zone)

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is used commercially as a fire retardant for flexible polyurethane foams. It was found to act both in the condensed (pyrolysis zone) and the vapor (flame) phases. The extent of its activity in the individual phases depends on the way in which the specimen is ignited. Under conditions of candle-like, top-down burning, retardation seems to occurs mainly in the condensed phase by a mechanism apparently based largely on the barrier properties of a phosphorus-containing carbonaceous layer that builds up on top of the liquid pyrolyzing layer beneath the flame. As the formation of this barrier requires time, extinguishment in this mode is relatively slow. Extinguishment is much faster in bottom-up burning, where the flame appears to be the main site of the retardation. In this mode, because of the orientation of the specimen relative to the flame, a disproportionately large amount of TDCPP enters the flame. It is proposed that TDCPP decomposition products, HCl and other low-fuel-value materials dilute the fuel vapors sufficiently to reduce their flame propagation velocity to below that at which they stream out of the pyrolysis zone. This pushes the flame away from the pyrolysis zone, uncoupling the thermal feedback mechanism that produces the fuel. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:231–254, 1998     

Confocal-based fluorescence fluctuation spectroscopy with a SPAD array detector

The combination of confocal laser-scanning microscopy(CLSM)and fluorescence fluctuation spectroscopy(FFS)is a powerful tool in studying fast,sub-resolution biomolecular processes in living cells.A detector array can further enhance CLSM-based FFS techniques,as it allows the simultaneous acquisition of several samples-essentially images-of the CLSM detection volume.However,the detector arrays that have previously been proposed for this purpose require tedious data corrections and preclude the combination of FFS with single-photon techniques,such as fluorescence lifetime imaging.Here,we solve these limitations by integrating a novel singie-photon-avalanche-diode(SPAD)array detector in a CLSM system.We validate this new implementation on a series of FFS analyses:spot-variation fluorescence correlation spectroscopy,pair-correlation function analysis,and image-derived mean squared displacement analysis.We predict that the unique combination of spatial and temporal information provided by our detector will make the proposed architecture the method of choice for CLSM-based FFS.     

Conductive coating films based on low density In2O3 powders and polymer latexes

Several kinds of conductive coating films were prepared from a low-density indium(III) oxide powder (which was employed because it provides a much higher volume for the same weight) and polymer latexes. The low-density In₂O₃, which is an electrically conductive pigment, was prepared by pyrolysis followed by the combustion of water-swellable polymer microspheres imbibed with In(NO₃)₃, the precursor of In₂O₃. Either acrylamide/N,N'-methylenebisacrylamide or poly(vinylalcohol)/glutaricdialdehyde was used to generate spherical hydrogel particles. The polymer latexes with which the In₂O₃ was mixed had a soft core and a hard shell structure to ensure that the coating film has suitable mechanical properties in addition to conductivity. Acrylonitrile/butadiene/styrene copolymer ABS or acrylonitrile/butylacrylate/styrene copolymer ABAS latexes were used as binders for the conductive pigment. The powder coating followed by hot pressing, the water-borne coating consisting of low-density In₂O₃ and polymer latexes followed by curing, or the colloidal dispersion coating was used to deposit flexible conductive coating films on polyester sheets. The conductive pigment density and the polymer latexes' size and flowability are the factors that affect the characteristics of the film. We found that the colloidal suspension coating procedure based on ABAS latexes achieves better electrical and mechanical properties for the coating films. © 1996 John Wiley & Sons, Inc.     

Physico‐chemical,organoleptic, antioxidative and release characteristics of flavoured yoghurt enriched with microencapsulated Melissa officinalis essential oil

In this research, Melissa officinalis essential oil was encapsulated through ultrasonication by using different ratios of whey protein isolate/sodium caseinate as coating material. Flavoured yoghurt was generated by adding microcapsules; the release behaviour of the essential oil was characterised over a 21‐day storage period. The released essential oil was quantified by dispersive liquid–liquid microextraction followed by gas chromatography. The results showed that the antioxidative activity of yoghurt samples was increased by the incorporation of encapsulated essential oil. Therefore, the use of microcapsules containing M. officinalis essential oil could be a suitable method for producing nutraceutical foods with antioxidant properties.