Volume 1 Issue 2
Authors: Pavel Raschman; Emilia Smincakova
Abstract: First stage of the hydrometallurgical production of antimony is leaching of the raw material that contains antimony-bearing mineral. The raw material can be ore or concentrate. Leaching can be carried out either in alkaline (Na2S+NaOH; NaOH) or acid (HCl; H2SO4; HF) solutions. In order to achieve good antimony recovery it is essential to leach the raw material under optimum conditions.Kinetics of the reaction between particulate stibnite and mixed Na2S + NaOH solutions were studied. The effects of concentrations of Na2S and NaOH, temperature, particle size and liquid-to-solid ratio were investigated. It was observed that the rate of leaching of stibnite: a) increased with an increase in both Na2S and NaOH concentration (from 0.5 wt. % to 2.0 wt. %), and temperature (from 292 K to 327 K); b) reached its maximum at Na2S: NaOH weight ratio equal to 1:1; c) decreased with an increase in particle size (from 40 μm to 500 μm) and L/S ratio (from 10 to 100). The results are presented in terms of the shrinking (nonreacted) core model and shrinking porous-particle model. Apparent activation energy is approximately 44 kJ mol-1 and the apparent reaction order for Na2S varies from 1.4 to 1.7. Calculated values of the kinetic parameters indicate that the leaching process is controlled by both intrinsic chemical reaction between Sb2S3 and Na2S at the liquid/solid interface, and pore diffusion.
Keywords: Stibnite, Kinetics, Alkaline leaching, Activation energy, Order of reaction
Authors: N. Mu’azu; A. Mustapha; A. Mohammed
Abstract: The building industry is the greatest consumer of energy worldwide, as such any measures taken by the industry to improve energy efficiency in our buildings will have a desirable effect in the reduction of carbon emissions into air. The paper discusses the concept of embodied energy or carbon of building materials as well as the concept of running or operational carbon. It further highlights strategies that could be used by the various stakeholders in the building industry; namely the building materials producers, builders, designers and governments to improve energy efficiency in buildings. It also shows that for the strategies to work, they must be part of a building industry policy in order to achieve an industry wide implementation of the measures.
Keywords: buildings, energy efficiency, embodied energy, embodied carbon, sustainability
Authors: M. V. Mallikarjun; Venkata Ramesh Mamilla; G. Lakshmi Narayana Rao
Abstract: Biodiesel was prepared from the non-edible oil of Karanja by transesterification of the crude oil with methanol in the presence of NaOH as catalyst. A maximum conversion of 92% (oil to ester) was achieved at 600c. Important fuel properties of methyl esters of biodiesel produced from karanja oil like viscosity, flash point ,fire point ,calorific value etc., was found out and compared to the properties of Indian standard biodiesel.
Keywords: Karanja oil, Biodiesel, Transesterification
Authors: Nan Zhang; Qinglin Meng
Abstract: A middle school in north china carries on reconstruction planning, uses of the Computational Fluid Dynamics method to simulate outdoor natural ventilation environment before and after its rebuilt, compares of simulation results. According to the result of that comparison, suggestions are advanced about human thermal comfort and energy conservation.
Keywords: computer simulation; wind environment; school planning; building energy conservation
Authors: Kun-Jung Hsu
Abstract: This paper analyses the changing path of primary energy use and emissions in Taiwan housing sector during 1982-2009. A key finding of the paper is that electricity was the major source of changing both in primary energy use and emission of the housing sector. During the study period, the annual logarithmic growth rate of the primary energy induced by electricity use in Taiwan housing sector was 6.45%. While the annual logarithmic growth rate of emissions from electricity used in housing sector was 7.82%. In which, about four-fifths of the growth rate came from electricity use, one-fifth came from emissions factor of electricity.
Keywords: primary energy use, greenhouse gases emissions, global warming potential, housing sector
Authors: Joonhong Lim; Meeseub Lim
Abstract: This paper describes the riding robot system named by "RideBot-II" which is a riding robot like as a horse. In order to simulate the riding motions, we developed the saddle mechanism which can generate 4 DOF motions including pitch, roll, bounce and slide movement, and also we controlled the riding motions and the intention of horseman. To generate the riding motions with the bodily sensation, we developed Novel Washout Filter and the algorithms for motion control. And also, we developed some health care service for the health care of horseman. A body state index was proposed that evaluates the personal health state from both the measured physiological variables and the surveyed questions. The physiological variables such as weight, blood pressure, heart rate variability(HRV), accelerated state photoplethysmograph (APG), body fat, and happiness index were measured by the specially designed bio-handle system and survey questions. The efficiency of the proposed ride robot is evaluated in the experiments.
Keywords: Riding Robot, Horseback Motions, Entertainment, Healthcare, Riding Motion Control.
Authors: Parisa Momen Roodaki; Abdolali Abdipour; Fatemeh Taghian; Abbas Mohammadi
Abstract: This paper presents the design and nonlinear analysis of a mm-wave wideband Doherty power amplifier at 22 to 29GHz with 7GHz bandwidth, the design is done using 0.15μm GaAs PHEMT transistor to support a variety of mm-wave applications including point to point digital radio, LMDS/LMCS , ka-band satellite spacecraft and ISM applications. The wideband Doherty power amplifier provides greater than 21dBm of output power across 22-29 GHz, with a typical PAE of 35% and typical gain 15dB over the frequency range. The designed Doherty power amplifier also showed acceptable linearity when induced with two tone signal. Analysis results show that the Doherty power amplifier significantly improves both efficiency and linearity in power amplifier in comparison with the main amplifier.
Keywords: wideband; millimeter wave; Doherty power amplifier; GaAS PHEMT
Authors: Abbas Mohammadi; Fatemeh Taghian; Parisa Momen Roodaki; Abdolali Abdipour
Abstract: This paper presents the design and simulation of an envelope tracking power amplifier (ET-PA) for 28 GHz LMDS applications. A linearization algorithm is also employed in digital domain in order to reduce the distortion of the system. Simulation shows that the proposed ET-PA delivers 19dBm output power with 21dB linear gain. Power added efficiency of this amplifier is more than 41% which shows about 15 percent efficiency enhancement compared to conventional LMDS PAs.
Keywords: envelope tracking; power amplifier; millimeter wave; LMDS; linearization; digital predistortion