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1.
Chilled cast iron tappet has a tendency microstructure of white, mottled and gray iron. The exact composition and other casting parameters, like pouring temperature, inoculation and coating, need to be determined for achieving the desired thickness of the chilled layer. Chilled cast iron finds applications in areas where improved hardness and wear resistance are required. Mottled cast iron has very poor machinability and high brittleness due to the presence of secondary cementite. These constitute the limitations for its use. The influence of inoculation, pouring temperature, coating thickness and chill plate on chilled depth was investigated. Taguchi design-of-experiments (DOE) are used for generating an optimal set of casting parameters to obtain a satisfactory chilled depth. Analysis of the effects of all the parameters on chilled depth has been carried out through a microstructure study. 相似文献
2.
Palanisamy GomathiAuthor VitaeMin Kwan KimAuthor Vitae Jung Je ParkAuthor VitaeDhanusuraman RagupathyAuthor Vitae Annamalai RajendranAuthor VitaeSoo Chool LeeAuthor Vitae Jae Chang KimAuthor VitaeSang Hak LeeAuthor Vitae Han Do GhimAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(2):897-902
Multiwalled carbon nanotubes (MWNTs) grafted chitosan (CS) nanowire (NW) was prepared by phase separation method. Glucose oxidase (GOx) was sequentially immobilized into MWNT-CS-NW to obtain MWNT-CS-NW/GOx biosensor. Field emission scanning electron microscopy (FESEM) images of MWNT-CS-NW/GOx reveals the existence of MWNT and CS. Cyclic voltammetry and amperometry were used to evaluate the electrochemical determination of glucose. The MWNT-CS-NW/GOx biosensor shows an excellent performance for glucose at +0.34 V with a high sensitivity (5.03 μA/mM) and lower response time (3 s) in a wide concentration range of 1-10 mM (correlation coefficient of 0.9988). In addition, MWNT-CS-NW/GOx biosensor possesses better reproducibility, storage stability and there is negligible interference from other electroactive components. 相似文献
3.
Optimisation and comparative study on the addition of shrimp protein hydrolysate and shrimp powder on physicochemical properties of extruded snack
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Annamalai Jeyakumari Mampuzha Sivadas Rahul Das Jaganath Bindu Chalil George Joshy Aliyamveetil Abubacker Zynudheen 《International Journal of Food Science & Technology》2016,51(7):1578-1585
The effect of an addition of shrimp protein hydrolysate and shrimp powder on the physicochemical properties of extruded snack was studied. Rice flour and cornflour were used as base materials, and extrusion was done using corotating twin‐screw extruder. A mixture response surface methodology was used to study the effect of ingredient mixture on the physical, functional and sensory properties of extrudates. Linear and quadratic mixture response regression model was fitted to the response variables, and it was evaluated using R2 values. Based on the desirability function score, the optimum combination of ingredient was 47.75% rice flour, 38.64% cornflour, 5.95% hydrolysate and 7.67% shrimp protein powder. It was observed that an addition of shrimp hydrolysate more than 5% (7.5%) improved the crispiness. Sensory evaluation revealed that shrimp hydrolysate and shrimp powder can be used at 5–7.5% level for developing protein‐rich extruded products without affecting sensory characteristics. 相似文献
4.
Wei Chen Kalyan Annamalai Jiafeng Sun Yuming Chen 《Korean Journal of Chemical Engineering》2016,33(8):2330-2336
Maximum volatile release (MVR) methods, including single point (MVR-S) and multiple (MVR-M) points, are proposed to extract the kinetics used to predict the fuel bean straw pyrolysis process. The simulation results were compared to those of the distributed activation energy model (DAEM). For the TGA (thermogravimetric analysis) experiments, fuels were heated from ambient temperature to 1,173 K at the heating rates of 10, 20, 40, 60, 80 K min?1, and the corresponding maximum volatile release points were obtained. For the MVR-S method, both the activation energy (E) and pre-exponential factor (B) increased with increasing heating rates. For the pyrolysis weight loss process, the DAEM showed best agreement with the experimental data, followed by the MVR-M, and then the MVR-S method. However, for weight loss rate prediction, MVR-S method had the best match with the experimental data, whereas the DAEM and MVR-M method generated more errors. 相似文献
5.
Open dumping site in Asian developing countries: a potential source of polychlorinated dibenz-p-dioxins and polychlorinated dibenzofurans 总被引:1,自引:0,他引:1
Nguyen HM Tu BM Watanabe M Kunisue T Monirith I Tanabe S Sakai S Subramanian A Sasikumar K Pham HV Bui CT Tana TS Prudente MS 《Environmental science & technology》2003,37(8):1493-1502
Open landfill dumping areas for municipal wastes in Asian developing countries have recently received particular attention with regard to environmental pollution problems. Because of the uncontrolled burning of solid wastes, elevated contamination by various toxic chemicals including dioxins and related compounds in these dumping sites has been anticipated. In this study, concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (PCBs) were determined in soils from dumping sites in the Philippines, Cambodia, India, and Vietnam. Residue concentrations of PCDD/Fs and coplanar PCBs in dumping site soils were apparently greater than those in soils collected in agricultural or urban areas far from dumping sites, suggesting that dumping sites are potential sources of PCDD/Fs and related compounds. Observed PCDD/F concentrations in soils from dumping sites in the Philippines and Cambodia were comparable or higher than those reported for dioxin-contaminated locations in the world (e.g., near the municipal waste incinerators and open landfill dumping sites). Homologue profiles of PCDD/Fs in dumping site soils from the Philippines and, to a lesser extent, from Cambodia and India reflected patterns of samples representing typical emissions, while profiles of agricultural or urban soils were similar to those of typical environmental sinks. This result suggests recent formation of PCDD/Fs in dumping site areas and that open dumping sites are a potential source of dioxins in Asian developing countries. Uncontrolled combustions of solid wastes by waste pickers, generation of methane gas, and low-temperature burning can be major factors for the formation of dioxins in dumping sites. Elevated fluxes of PCDD/Fs to soils in dumping sites were encountered in the Philippines, Cambodia, India, and Vietnam-Hanoi, and these levels were higher than those reported for other countries. Considerable loading rates of PCDD/Fs in the dumping sites of these countries were observed, ranging from 20 to 3900 mg/yr (0.12-35 mg TEQ/yr). PCDD/F concentrations in some soil samples from the Philippines, Cambodia, India, and Vietnam-Hanoi exceeded environmental guideline values, suggesting potential health effects on humans and wildlife living near these dumping sites. The estimated intakes of dioxins via soil ingestion and dermal exposure for children were higher than those for adults, suggesting greater risk of dioxin exposure for children in dumping sites. To our knowledge, this is the first comprehensive study on PCDD/Fs contamination in open dumping sites of Asian developing countries. On the basis of the result of this study, we have addressed a new environmental issue that open dumping sites are potential sources of PCDD/Fs and related compounds, and dioxin contamination in dumping sites may become a key environmental problem in developing countries. 相似文献
6.
Dielectric properties of thin polycrystalline and amorphous films of NiO, NiO(Li), CoO, CoO(Li), Nb2O5 and TiO2 in the thickness range 0.14–15 ωm were studied as a function of frequency, temperature, applied voltage and dopant concentration in the frequency range 3–108 Hz. These films were prepared either by anodization or thermal oxidation and in some cases by reactive sputtering. Experimental data for the real ?1 and imaginary ?2 parts of the dielectric constant, ac conductivity σ(ω) and loss tangent tan δ indicate the existence of several dispersion mechanisms. Cole-Cole plots and the modified Debye relations were used to derive the values for relaxation times at low frequencies. The frequency dependence of σ(ω) in the frequency region 103–106 Hz where σ(ω)αωn indicates that the dispersion mechanism is due to charge carriers hopping between sites with either correlated or non-correlated potentials. The observed quadratic dependence of σ(ω) on frequency in the frequency region 106–108 Hz is attributed to a Debye type loss resulting from thermally activated hopping. Polarization effects at lower frequencies <103Hz indicate the existence of Schottky barriers at the metal-insulator interfaces in agreement with Simmons theory of MIM structures. 相似文献
7.
Flow injection analysis of an ultratrace amount of arsenite using a Prussian blue-modified screen-printed electrode 总被引:1,自引:0,他引:1
We report here a new electrochemical method for the selective detection of ultratrace amount of arsenite (AsO(2)(-), As(3+)) using a Prussian blue-modified screen-printed electrode (designated as PBSPE) by flow injection analysis (FIA) in 0.1 M, pH 4 KCl/HCl carrier solution. The Prussian yellow/Prussian blue redox couple of the PBSPE was found to mediate the As(3+) oxidation. Various factors influencing the determination of As(3+) were thoroughly investigated in this study. Under the optimized FIA conditions, a linear calibration plot in the range of 50 nM-300 microM with a detection limit (S/N = 3) of 25 nM (i.e., 64.9 pg in 20-microL loop) was observed at an operation potential of +0.6 V vs Ag/AgCl. The sensitivity was good enough to detect arsenite at levels lower than the current EPA standard. This modified electrode showed good resistance to interference from common ions, especially Cl(-), which is generally considered as a major interference in the determination of As(3+) by ICPMS. The practical utility of the PBSPE to detect As(3+) was demonstrated in "blackfoot" disease endemic village groundwater from the southwestern coast area of Taiwan (Pei-Men). 相似文献
8.
Harmonization of global third generation mobile systems 总被引:1,自引:0,他引:1
The International Telecommunication Union launched the third-generation project in 1986 with the aim to provide global personal communication using an inexpensive mobile terminal that can truly facilitate communication "anywhere, anytime". In previous years, standardization activities toward IMT-2000 have accelerated toward concrete specifications. By June 1998, a total of 15 proposals from around the world had been submitted to the ITU as radio transmission technology candidates. Since then, the 3G standardization landscape has seen many changes-a steady progression of the convergence process. This article provides a comprehensive overview of the worldwide harmonization efforts on the standardization of third-generation terrestrial mobile communication systems. The status, as of October 1999 when this article was written, of the technical specifications within 3G partnership projects are also summarized. 相似文献
9.
Signal fading is a ubiquitous problem in mobile and wireless communications. In digital systems, fading results in bit errors, and evaluating the average error rate under fairly general fading models and multichannel reception is often required. Predominantly to date, most researchers perform the averaging using the probability density function method or the moment generating function (MGF) method. This paper presents a third method, called the characteristic function (CHF) method, for calculating the average error rates and outage performance of a broad class of coherent, differentially coherent, and noncoherent communication systems, with or without diversity reception, in a myriad of fading environments. Unlike the MGF technique, the proposed CHF method (based on Parseval's theorem) enables us to unify the average error-rate analysis of different modulation formats and all commonly used predetection diversity techniques (i.e., maximal-ratio combining, equal-gain combining, selection diversity, and switched diversity) within a single common framework. The CHF method also lends itself to the averaging of the conditional error probability involving the complementary incomplete Gamma function and the confluent hypergeometric function over fading amplitudes, which heretofore resisted to a simple form. As an aside, we show some previous results as special cases of our unified framework. 相似文献
10.