The design of multiple feedback topology Chebyshev low-pass active filter with average differential evolution algorithm

Neural Computing and Applications - This study presents the design of a tenth-order multiple feedback Chebyshev low-pass filter (MF-C-LPF). Component selection and gain calculation of filters are...     

Effects of dowels produced from various materials on withdrawal strength in MDF and Pb

Wood dowels are commonly used in the construction furniture, but little information is available about the additive effects of dowels on the ultimate withdrawal strength of single or multidowel joints. This study was carried out to determine the tensile strength of 10‐mm‐diameter dowels produced from medium‐density fiberboard (MDF), plywood, scotch pine (Pinus sylvestris L.), and beech (Fagus orientalis lipsky), bonded parallel and vertical to the surface of MDF and particleboard (Pb) with poly(vinyl acetate) (PVAc) and Desmodur‐VTKA (D‐VTKA). Tensile strength was applied to the dowels according to the procedure in the ASTM‐D 1037 standard. The effects of dowel species, direction of tensile, composite material, and type of adhesive on tensile strength were determined. The results showed that the highest tensile strength was obtained in beech dowels bonded vertically with PVAc adhesive to the surface of MDF at 7.91 N/mm². If the dowels used in furniture production are subjected to great tensile strength, beech dowels bonded with PVAc adhesive on MDF should be used. However, when dowels produced from MDF and plywood waste are used, they also can produce positive results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 531–535, 2003     

Combustion properties of laminated veneer lumbers bonded with PVAc,PF adhesives and impregnated with some fire retardants

In this study, the effects of impregnation materials di‐ammonium phosphate, aluminium sulphate, potassium carbonate, calcium chloride, zinc chloride on combustion properties of 3 ply laminated veneer lumbers (LVL) produced from Walnut (Juglans regia L.) using phenol–formaldehyde (PF), poly (vinyl acetate) have been investigated. The pressure‐vacuum method was used for impregnation process. Combustion test was performed according to the procedure of ASTM‐E 69 standards. During the test, mass reduction, temperature and released gas (CO, NO_X, SO₂, O₂) were determined every 30 s. As a result, zinc chloride was found to be the most successful fire‐retardant chemical in LVL at PF adhesive. Since it diminishes combustion, the fire retardant of LVL produced from walnut using PF adhesive can be advised. Copyright © 2009 John Wiley & Sons, Ltd.     

Simultaneous removal of C, N, P from cheese whey by jet loop membrane bioreactor (JLMBR)

The membrane bioreactor (MBR) used in this study consisted of a jet loop bioreactor (aerobic high rate system) and a membrane separation unit (microfiltration). Jet loop membrane bioreactor (JLMBR) system is a high performance treatment system. High organic loading rates can be achieved with a very small footprint. The JLMBR is a compact biological treatment system which requires much smaller tank volumes than conventional activated sludge system. Solid-liquid separation is performed with a membrane. The JLMBR system, of 35 L capacity, was operated continuously for 3 months with a sludge age of 1.1-2.8 days and chemical oxygen demand (COD) loads of 3.5-33.5 kg COD m(-3) day(-1). The mean concentration values of COD, total nitrogen (TN) and PO(4)3- in cheese whey (CW) were found as 78,680 mg L(-1), 1125 mg L(-1) and 378 mg L(-1), respectively. Ninety-seven percent COD removal rate was obtained at the sludge age (Thetac) of 1.6 days and volumetric loads of 22.2 kg COD m(-3) day(-1). TN removal was obtained as 99% at the loading rates of 17-436 g TN m(-3) day(-1). PO4(3-) removals were between 65 and 88% for the loading of 30-134 gPO4(3-) m(-3) day(-1). The system could simultaneously remove the COD, TN and PO(4)3- at high efficiencies. The sludge flocks were highly motile, dispersed and had poor settling properties.     

The effect of steam treatment on bonding strength of impregnated wood materials

In wood materials, the species of wood, its humidity, and the type of the adhesive have an important role to make the wood material durable for a long period both in inner space and outer space. In this study, it is aimed to determine the resistance characteristics of adhesive using different impregnation chemicals and different types of adhesives before and after steam treatment. In this study, beech and poplar as wood materials; mixture of Protim-WR 235, Tanalith-C, and Celcure-AC 500 as impregnation materials; and poly vinyl acetate (PVAc), urea formaldehyde (UF), and desmodur vinyl trie ketonol acetate (D-VTKA), resistant to water, as adhesives materials were used. All samples were kept in a steaming equipment for 2, 6, 12, 24, 48, and 96?h, afterwards the maximum force of the samples were measured for each waiting period, and then their bonding strength was determined. According to the results of the study, beech control samples had higher strength than poplar control samples. Control samples bonded with D-VTKA is the least affected one compared to all original control samples in the steam test. D-VTKA can be offered as the proper adhesive for humid places. The results also showed that Tanalith-C is the least affecting impregnation material on the bonding strength.     

EFFECT OF RESIDENCE TIME ON FULLERENE YIELD

Although there exists no general agreement on mechanistic pathways for fullerene formation, there are some reasonable schemes in the literature explaining most of the features. However, as far as the existing production processes and the final yields are concerned, not the formation but rather chemical stabilization of the relatively hot products was more influence on the final production yield. A continuous helium jet was blown into the reactive zone by a quartz microprobe located 20 mm away from the arc to enhance rapid removal of the products from the high temperature zone. Decreased residence times appear to improve production efficiency.     

SIMULTANEOUS DETERMINATION OF C60 AND C70 FULLERENES BY A SPECTROPHOTOMETRIC METHOD

In all fullerene-producing systems, reaction products were black soot extracts reported to contain a 5-25% fullerene mixture. Toluene extraction of the soot results in a solution of C₆₀, C₇₀, and higherc fullerenes. Without separation, absolute determination of the contents is not possible, leaving the researcher to comment only on the C₆₀/C₇₀ ratio of the solution. High-performance liquid chromatography, nuclear magnetic resonance, and scanning tunneling microscopy imaging techniques were reported in the literature for determining the C₆₀/C₇₀ ratio of the mixtures. These methods require tedious experiments and produce slightly differing results as well. In this communication, a new and relatively quick method is proposed for the simultaneous determination of the yields of C₆₀ and C₇₀ (not the ratio) in fullerene-containing solutions by ultraviolet-visible spectrophotometric analysis.     

Piezoelectric actuator for mobile auto focus camera applications

Recently, various multimedia devices such as MP3 player, camera and even TV are integrated into a mobile phone. Consumer demands image cameras in mobile phone to have similar quality and performance as those of dedicated digital cameras. For a good image quality, increasing of resolution requires optical auto focusing, where a small lens group needs to be moved in a limited volume. Due to the efforts for reducing the size of each component in mobile phone, many types of motors have been investigated to achieve AF or zooming functions. However, a motor should be able to provide high controllability and performance to perform auto-focus (AF) camera function. One of the important features that piezoelectric motors have is the ability to maintain moving element position when the motor is not electrically excited. For mobile device application where power consumption is critical, this feature is fitting very well for lens positioning application in phone cameras. In this paper, we have applied our own development of piezoelectric motor for auto focus phone cameras. During auto focusing, we have measured total motor operating time that is less than one percent of total auto focusing time. Average instantaneous power, which is about 65 mWatts, is consumed only when the motor operates, which make piezoelectric motors to be superior over electromagnetic counterparts in terms of energy efficiency.     

Thermodynamic analysis of an existing coal-fired power plant for district heating/cooling application

In a conventional coal-fired power plant, which is only designed for electricity generation, 2/3 of fuel energy is wasted through stack gases and cooling water of condensers. This waste energy could be recovered by trigeneration; modifying the plants in order to meet district heating/cooling demand of their locations. In this paper, thermodynamical analysis of trigeneration conversion of a public coal-fired power plant, which is designed only for electricity generation, has been carried out. Waste heat potentials and other heat extraction capabilities have been evaluated. Best effective steam extraction point for district heating/cooling system; have been identified by conducting energetic and exergetic performance analyses. Analyses results revealed that the low-pressure turbine inlet stage is the most convenient point for steam extraction for the plant analyzed.     

Effect of dowels and adhesive types on withdrawal strength in particleboard and MDF

Composite materials and wooden dowels are being used increasingly in the construction of furniture frames and inner decoration. However, there is little information available concerning the withdrawal strength of various fasteners and in particular, dowels in these materials. The aim of this study was to determine the withdrawal strengths of 6, 8, and 10?mm diameter dowels produced from different wood species bonded parallel or vertical to the surfaces of a medium-density fiberboard (MDF) or particleboard with poly vinylacetate or Desmodur (D-VTKA). According to TS 4539 standard, the effect of dowel species, direction of withdrawal, board type and the type of adhesive on the withdrawal strength were determined. The highest (8.35?N/mm²) withdrawal strength was obtained for oak dowels bonded with D-VTKA adhesive vertically to the surface of MDF. This value is higher than the predictive expression that allows designers to estimate the withdrawal strength of dowels.