Search results for: grain refinement

Authors: Mogale T. E., Ayisi K. K., Munjonji L., Kifle Y. G.

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Grain sorghum and cowpea are important staple crops in many areas of South Africa, particularly the Limpopo Province. The two crops are produced under a wide range of unsustainable conventional methods, which reduces productivity in the long run. Climate-smart traditional methods such as intercropping can be adopted to ensure sustainable production of these important two crops in the province. A no-tillage field experiment was laid out in a randomised complete block design (RCBD) with four replications over two seasons in two distinct agro-ecological zones, Syferkuil and Ofcolacoin, the province to assess the productivity of sorghum-cowpea intercropped under two cowpea densities.LCi Ultra compact photosynthesis machine was used to collect photosynthetic rate data biweekly between 11h00 and 13h00 until physiological maturity. Biomass and grain yield of the component crops in binary and sole cultures were determined at harvest maturity from middle rows of 2.7 m2 area. The biomass was oven dried in the laboratory at 65oC till constant weight. To obtain grain yield, harvested sorghum heads and cowpea pods were threshed, cleaned, and weighed. Harvest index (HI) and land equivalent ratio (LER) of the two crops were calculated to assess intercrop productivity relative to sole cultures. Data was analysed using the statistical analysis software system (SAS) 9.4 version, followed by mean separation using the least significant difference method. The photosyntheticrate of sorghum-cowpea intercrop was influenced by cowpea density and sorghum cultivar. Photosynthetic rate under low density was higher compared to high density, but this was dependent on the growing conditions. Dry biomass accumulation, grain yield, and harvest index differed among the sorghum cultivars and cowpea in both binary and sole cultures at the two test locations during the 2018/19 and 2020/21 growing seasons. Cowpea grain and dry biomass yields werein excess of 60% under high density compared to low density in both binary and sole cultures. The results revealed that grain yield accumulation of sorghum cultivars was influenced by the density of the companion cowpea crop as well as the production season. For instant, at Syferkuil, Enforcer and Ns5511 accumulated high yield under low density, whereas, at Ofcolaco, the higher yield was recorded under high density. Generally, under low cowpea density, cultivar Enforcer produced relatively higher grain yield whereas, under higher density, Titan yield was superior. The partial and total LER varied with growing season and the treatments studied. The total LERs exceeded 1.0 at the two locations across seasons, ranging from 1.3 to 1.8. From the results, it can be concluded that resources were used more efficiently in sorghum-cowpea intercrop at both Syferkuil and Ofcolaco. Furthermore, intercropping system improved photosynthetic rate, grain yield, and dry matter accumulation of sorghum and cowpea depending on growing conditions and density of cowpea. Hence, the sorghum-cowpea intercropping system can be adopted as a climate-smart practice for sustainable production in the Limpopo province.

Keywords: cowpea, climate-smart, grain sorghum, intercropping

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Authors: Peter Jurči, Jana Ptačinová, Mária Hudáková, Mária Dománková, Martin Kusý, Martin Sahul

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The strength, hardness, and toughness (ductility) are in strong conflict for the metallic materials. The only possibility how to make their simultaneous improvement is to provide the microstructural refinement, by cold deformation, and subsequent recrystallization. However, application of this kind of treatment is impossible for high-carbon high-alloyed ledeburitic tool steels. Alternatively, it has been demonstrated over the last few years that sub-zero treatment induces some microstructural changes in these materials, which might favourably influence their complex of mechanical properties. Commercially available PM ledeburitic steel Vanadis 6 has been used for the current investigations. The paper demonstrates that sub-zero treatment induces clear refinement of the martensite, reduces the amount of retained austenite, enhances the population density of fine carbides, and makes alterations in microstructural development that take place during tempering. As a consequence, the steel manifests improved wear resistance at higher toughness and fracture toughness. Based on the obtained results, the key question “can the wear performance be improved by sub-zero treatment simultaneously with toughness” can be answered by “definitely yes”.

Keywords: ledeburitic tool steels, microstructure, sub-zero treatment, mechanical properties

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Authors: Trishita Ray, Ashok Perka, Arnab Karani, M. Shome, Saurabh Kundu

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Line pipe steels are used for long distance transportation of crude oil and gas under extreme environmental conditions. Welding is necessary to lay large scale pipelines. Coarse Grain Heat Affected Zone (CGHAZ) of a welded joint exhibits worst toughness because of excessive grain growth and brittle microstructures like bainite and martensite, leading to early failure. Therefore, it is necessary to investigate microstructures and properties of the CGHAZ for different welding heat inputs. In the present study, CGHAZ for two heat inputs of 10 kJ/cm and 50 kJ/cm were simulated in Gleeble 3800, and the microstructures were investigated in detail by means of Scanning Electron Microscopy (SEM) and Electron Backscattered Diffraction (EBSD). Charpy Impact Tests were also done to evaluate the impact properties. High heat input was characterized with very low toughness and massive prior austenite grains. With the crystallographic information from EBSD, the area of a single prior austenite grain was traced out for both the welding conditions. Analysis of the prior austenite grains showed the formation of high angle boundaries between the crystallographic packets. Effect of these packet boundaries on secondary cleavage crack propagation was discussed. It was observed that in the low heat input condition, formation of finer packets with a criss-cross morphology inside prior austenite grains was effective in crack arrest whereas, in the high heat input condition, formation of larger packets with higher volume of low angle boundaries failed to resist crack propagation resulting in a brittle fracture. Thus, the characteristics in a crystallographic packet and impact properties are related and should be controlled to obtain optimum properties.

Keywords: coarse grain heat affected zone, crystallographic packet, toughness, line pipe steel

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Authors: J. I. Aguwa, S. Sadiku, M. Abdullahi

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This study examined the structural reliability of the Nigerian grown Opepe timber as bridge beam material. The strength of a particular specie of timber depends so much on some factors such as soil and environment in which it is grown. The steps involved are collection of the Opepe timber samples, seasoning/preparation of the test specimens, determination of the strength properties/statistical analysis, development of a computer programme in FORTRAN language and finally structural reliability analysis using FORM 5 software. The result revealed that the Nigerian grown Opepe is a reliable and durable structural bridge beam material for span of 5000mm, depth of 400mm, breadth of 250mm and end bearing length of 150mm. The probabilities of failure in bending parallel to the grain, compression perpendicular to the grain, shear parallel to the grain and deflection are 1.61 x 10^-7, 1.43 x 10^-8, 1.93 x 10^-4 and 1.51 x 10^-15 respectively. The paper recommends establishment of Opepe plantation in various Local Government Areas in Nigeria for structural applications such as in bridges, railway sleepers, generation of income to the nation as well as creating employment for the numerous unemployed youths.

Keywords: bending and deflection, bridge beam, compression, Nigerian Opepe, shear, structural reliability

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Authors: Li Long, Thomas Ortlepp

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A theoretical model for the optimization of thermopile sensor performance is developed for thermoelectric-based infrared radiation detection. It is shown that the performance of polycrystalline silicon film thermopile sensor can be optimized according to the thermoelectric quality factor, sensor layer structure factor, and sensor layout geometrical form factor. Based on the properties of electrons, phonons, grain boundaries, and their interactions, the thermoelectric quality factor of polycrystalline silicon is analyzed with the relaxation time approximation of the Boltzmann transport equation. The model includes the effect of grain structure, grain boundary trap properties, and doping concentration. The layer structure factor is analyzed with respect to the infrared absorption coefficient. The optimization of layout design is characterized by the form factor, which is calculated for different sensor designs. A double-layer polycrystalline silicon thermopile infrared sensor on a suspended membrane has been designed and fabricated with a CMOS-compatible process. The theoretical approach is confirmed by measurement results.

Keywords: polycrystalline silicon, relaxation time approximation, specific detectivity, thermal conductivity, thermopile infrared sensor

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Authors: Mihriban Korukluoglu, Goksen Arik, Cagla Erdogan, Selen Kocakoglu

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Kefir is a traditional fermented refreshing beverage which is known for its valuable and beneficial properties for human health. Mainly yeast species, lactic acid bacteria (LAB) strains and fewer acetic acid bacteria strains live together in a natural matrix named “kefir grain”, which is formed from various proteins and polysaccharides. Different microbial species live together in slimy kefir grain and it has been thought that synergetic effect could take place between microorganisms, which belong to different genera and species. In this research, yeast and LAB were isolated from kefir samples obtained from Uludag University Food Engineering Department. The cell morphology of isolates was screened by microscopic examination. Gram reactions of bacteria isolates were determined by Gram staining method, and as well catalase activity was examined. After observing the microscopic/morphological and physical, enzymatic properties of all isolates, they were divided into the groups as LAB and/or yeast according to their physicochemical responses to the applied examinations. As part of this research, the antagonistic/synergistic efficacy of the identified five LAB and five yeast strains to each other were determined individually by disk diffusion method. The antagonistic or synergistic effect is one of the most important properties in a co-culture system that different microorganisms are living together. The synergistic effect should be promoted, whereas the antagonistic effect is prevented to provide effective culture for fermentation of kefir. The aim of this study was to determine microbial interactions between identified yeast and LAB strains, and whether their effect is antagonistic or synergistic. Thus, if there is a strain which inhibits or retards the growth of other strains found in Kefir microflora, this circumstance shows the presence of antagonistic effect in the medium. Such negative influence should be prevented, whereas the microorganisms which have synergistic effect on each other should be promoted by combining them in kefir grain. Standardisation is the most desired property for industrial production. Each microorganism found in the microbial flora of a kefir grain should be identified individually. The members of the microbial community found in the glue-like kefir grain may be redesigned as a starter culture regarding efficacy of each microorganism to another in kefir processing. The main aim of this research was to shed light on more effective production of kefir grain and to contribute a standardisation of kefir processing in the food industry.

Keywords: antagonistic effect, kefir, lactic acid bacteria (LAB), synergistic, yeast

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Authors: Shafique Qadir Memon, Muhammad Safar Mirjat, Abdul Quadir Mughal, Nadeem Amjad

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The aims of this study were to determine direct input energy and indirect energy in maize production, to evaluate the inputs energy consumption and outputs energy gained for maize production in Islamabad, Pakistan for spring 2013. Results showed that grain yield was maximum under deep tillage as compared to conventional and zero tillage. Total energy input/output were maximum in deep tillage as compared to conventional tillage while lowest in zero tillage, net energy gain were found maximum under deep tillage.

Keywords: tillage, energy, grain yield, net energy gain

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Authors: Niloufar Khoshbakht, Peggi L. Clouston, Sanjay R. Arwade, Alexander C. Schreyer

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Laminated veneer bamboo (LVB) is a structural engineered composite made from glued layers of bamboo. A relatively new building product, LVB is currently employed in similar sizes and applications as dimensional lumber. This study describes the results of a 3D elastic Finite Element model for halfhole specimens when loaded in compression parallel-to-grain per ASTM 5764. The model simulates LVB fracture initiation due to shear stresses in the dowel joint and predicts displacement at failure validated through comparison with experimental results. The material fails at 1mm displacement due to in-plane shear stresses. The paper clarifies the complex interactive state of in-plane shear, tension perpendicular-to-grain, and compression parallel-to-grain stresses that form different distributions in the critical zone beneath the bolt hole for half-hole specimens. These findings are instrumental in understanding key factors and fundamental failure mechanisms that occur in LVB dowel connections to help devise safe standards and further LVB product adoption and design.

Keywords: composite, dowel connection, embedment strength, failure behavior, finite element analysis, Moso bamboo

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Authors: A. Bahrani

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In order to study the effect of restricted irrigation systems and different potassium fertilizer on water use efficiency and yield of rapeseed (Brassica napus L.), an experiment was conducted in an arid area in Khuzestan, Iran in 2013. The main plots consisted of three irrigation methods: FI (full irrigation), alternate furrow irrigation (AFI) and fixed furrow irrigation (FFI). Each subplot received three rates of K fertiliser application: 0, 150 or 300 kg ha-1. The results showed that the plots receiving the full irrigation resulted in significantly higher grain yields, 1000-kernel weight and grain number per pod than both alternate treatments. However, the highest WUE were obtained in alternate furrow irrigation and 300 kg K ha-1 and the lowest one was found in the FI treatment and 0 kg K ha-1. Potassium application increased RWC in alternate furrow irrigation and fixed furrow irrigation than FI treatment. Maximum oil content was observed in those treatments where full irrigation was applied while minimum oil content was produced in FFI irrigated treatments. Potassium fertilizer also increased grain oil by 15 % than control. Deficit irrigation reduced oleic acid and erucic acid. However, oleic acid and linoleic acid increased with increasing of potassium.

Keywords: erucic acid, irrigation methods, linoleic acid, oil percent, oleic acid

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Authors: Aleksandr Kalinenko, Igor Vysotskiy, Sergey Malopheyev, Sergey Mironov, Rustam Kaibyshev

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From a thermo-mechanical standpoint, friction-stir welding (FSW) represents a unique combination of very large strains, high temperature and relatively high strain rate. The material behavior under such extreme deformation conditions is not studied well and thus, the microstructural examinations of the friction-stir welded materials represent an essential academic interest. Moreover, a clear understanding of the microstructural mechanisms operating during FSW should improve our understanding of the microstructure-properties relationship in the FSWed materials and thus enables us to optimize their service characteristics. Despite extensive research in this field, the microstructural behavior of some important structural materials remains not completely clear. In order to contribute to this important work, the present study was undertaken to examine the grain structure evolution during the FSW of 6061-T6 aluminum alloy. To provide an in-depth insight into this process, the electron backscatter diffraction (EBSD) technique was employed for this purpose. Microstructural observations were conducted by using an FEI Quanta 450 Nova field-emission-gun scanning electron microscope equipped with TSL OIMTM software. A suitable surface finish for EBSD was obtained by electro-polishing in a solution of 25% nitric acid in methanol. A 15° criterion was employed to differentiate low-angle boundaries (LABs) from high-angle boundaries (HABs). In the entire range of the studied FSW regimes, the grain structure evolved in the stir zone was found to be dominated by nearly-equiaxed grains with a relatively high fraction of low-angle boundaries and the moderate-strength B/-B {112}<110> simple-shear texture. In all cases, the grain-structure development was found to be dictated by an extensive formation of deformation-induced boundaries, their gradual transformation to the high-angle grain boundaries. Accordingly, the grain subdivision was concluded to the key microstructural mechanism. Remarkably, a gradual suppression of this mechanism has been observed at relatively high welding temperatures. This surprising result has been attributed to the reduction of dislocation density due to the annihilation phenomena.

Keywords: electron backscatter diffraction, friction-stir welding, heat-treatable aluminum alloys, microstructure

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Authors: Mayowa Philips Ibitola, Abe Oluwaseun Banji, Olorunfemi Akinade-Solomon

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A total of 20 bottom sediment samples were collected from the Lekki Lagoon during the wet and dry season. The study was carried out to determine the textural characteristics, sediment distribution pattern and energy of transportation within the lagoon system. The sediment grain sizes and depth profiling was analyzed using dry sieving method and MATLAB algorithm for processing. The granulometric reveals fine grained sand both for the wet and dry season with an average mean value of 2.03 ϕ and -2.88 ϕ, respectively. Sediments were moderately sorted with an average inclusive standard deviation of 0.77 ϕ and -0.82 ϕ. Skewness varied from strongly coarse and near symmetrical 0.34- ϕ and 0.09 ϕ. The kurtosis average value was 0.87 ϕ and -1.4 ϕ (platykurtic and leptokurtic). Entirely, the bathymetry shows an average depth of 4.0 m. The deepest and shallowest area has a depth of 11.2 m and 0.5 m, respectively. High concentration of fine sand was observed at deep areas compared to the shallow areas during wet and dry season. Statistical parameter results show that the overall sediments are sorted, and deposited under low energy condition over a long distance. However, sediment distribution and sediment transport pattern of Lekki Lagoon is controlled by a low energy current and the down slope configuration of the bathymetry enhances the sorting and the deposition rate in the Lekki Lagoon.

Keywords: Lekki Lagoon, Marine sediment, bathymetry, grain size distribution

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Authors: Azizul Haque, Kamrun Nahar

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Field experiments were conducted to reduce the chemical fertilizers with the integrated use of straight and phospho- vermicompost with chemical fertilizers in T. aman-Boro rice cropping pattern at the BINA farm, Mymensingh during 2019-20. Six treatments were used in the experiment for both the crops. The treatments used for T. aman rice (Binadhan 17) with straight vermicompost were as follows: T1: Native soil fertility, T2: 100% N from Chemical Fertilizer (CF), T3:70%N from CF, T4: 30% N from vermicompost-3 + 70% N from CF and T5:30% N from vermicompost-4 + 70% N from CF and T6: 100% PKS only. The treatments of Boro rice (var. Binadhan -10) with phospho-vermicompost were: T1: Native soil fertility, T2: 100% NPKS from chemical fertilizer (CF), T3:75% NKS from CF (Non IPNS) with 1 t ha-1 Phospho-vermicompost (P-Vermicom), T4: 100% NKS (IPNS) with 2 t ha-1 P-Vermicom, T5: 100% NKS from CF (Non IPNS) with 2 t ha-1 P-Vermicom and T6: 100% NKS. The experiments were conducted in a Randomized Complete Block Design with three replications. The treatment T5 (5.5 t ha-1) gave maximum grain yield of T.aman rice followed by the treatment T4 (5.4 t ha-1). But the treatmentsT5, T4, and T2 gave identical grain yields of T. aman rice. Similar results were observed in case of straw yields of T. Aman rice. The result indicated that 70% N from CF with 30% N from either straight vermicompost-3 or straight vermicompost-4 gave comparable yield to the sole application of 100% N from CF alone. Therefore, 30% chemical fertilizers (N, P, K and S) could be saved with the integrated (IPNS) use of vermicompost-3 or vermicompost-4 in the cultivation of T. aman rice. Application of Phospho-vermicompost significantly influenced the yield and yield contributing characters of Boro rice (Binadhan-10). The treatment T4 (7.23.0 t ha-1) gave maximum grain yield of Boro rice followed by the treatments T2 and T5. But the treatments T2 and T5 produced statistically similar grain yields. The results from the treatment T4 (100% NKS (IPNS) with 2.0 t ha-1P-Vermicom) indicated that full demand of P could be met up from 2 t ha-1 Phospho-vermicompost with IPNS chemical fertilizers (NKS) which was sufficient for attaining the highest grain yield of Boro rice than that of the treatment T2 (100% NPKS from CF) and the treatmentT5 (100% NKS from CF (Non IPNS) + 2 t ha-1 Phospho-vermicompost). The results revealed that 100% P and substantial amount of N (21%), K (44.6%) and S (53.7%) fertilizers could be saved with the integrated use of Phospho-vermicompost in the cultivation of Boro rice. In case of Boro rice partial cost benefit analysis showed that the application of Phospho-vermicompost (@2 tha--1) with IPNS chemical fertilizes (NKS) gave higher return of Tk. 18,213 / - than that of only 100% chemical fertilizer. Therefore, use of Phospho-vermicompost was beneficial for the cultivation of Boro rice in combination with suitable dose of chemical fertilizers.

Keywords: phosphovermicompost, cropping pattern, rice yield, chemical fertilizer

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Authors: Sarakorn Sukaviriya

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This paper describes the inspection procedure, root cause analysis, the rectification of crack, and how to apply the procedure with other similar plants. During the operation of the steam turbine (620MW), instruments such as speed sensor of steam turbine, the servo valve of main stop valve and electrical wires were malfunction caused by leakage steam from main steam governing valve. Therefore, the power plant decided to shutdown steam turbines for figuring out the cause of leakage steam. Inspection techniques to be applied in this problem were microstructure testing (SEM), pipe stress analysis (FEM) and non-destructive testing. The crack was initially found on main governing valve’s weldment by visual inspection. To analyze more precisely, pipe stress analysis and microstructure testing were applied and results indicated that the crack was intergranular and originated from the weld defect. This weld defect caused the notch with high-stress concentration which created crack and then propagated to steam leakage. The major root cause of this problem was an inappropriate welding process, which created a weld defect. To repair this joint from damage, we used a welding technique by producing refinement of coarse grain HAZ and eliminating stress concentration. After the weldment was completely repaired, other adjacent weldments still had risk. Hence, to prevent any future cracks, non-destructive testing (NDT) shall be applied to all joints in order to ensure that there will be no indication of crack.

Keywords: steam-pipe leakage, steam leakage, weld crack analysis, weld defect

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Authors: Radheshyam Yadav, Ramakrishna Wusirika

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Plant Growth Promoting Bacteria (PGPB) and Arbuscular Mycorrhizal (AM) Fungi are ubiquitous in soil and often very critical for crop yield and agriculture sustainability, and this has motivated the agricultural practices to support and promote PGPB and AM Fungi in agriculture. PGPB can be involved in a range of processes that affect Nitrogen (N) and Phosphorus (P) transformations in soil and thus influence nutrient availability and uptake to the plants. A field study with two wheat cultivars, HD-3086, and HD-2967 was performed in Malwa region, Bathinda of Punjab, India, to evaluate the effect of native and non-native PGPB alone and in combination with AM fungi as an inoculant on wheat grain yield, nutrient uptake and soil health parameters (dehydrogenase, urease, β‐glucosidase). Our results showed that despite an early insignificant increase in shoot length, plants treated with PGPB (Bacillus sp.) and AM Fungi led to a significant increase in shoot growth at maturity, aboveground biomass, nitrogen (45% - 40%) and phosphorus (40% - 34%) content in wheat grains relative to untreated control plants. Similarly, enhanced grain yield and nutrients uptake i.e. copper (27.15% - 36.25%) iron (43% - 53%) and zinc (44% - 47%) was recorded in PGPB and AM Fungi treated plants relative to untreated control. Overall, inoculation with native PGPB alone and in combination with AM Fungi provided benefits to enhance grain yield, wheat biofortification, and improved soil fertility, despite this effect varied depending on different PGPB isolates and wheat cultivars. These field study results provide evidence of the benefits of agricultural practices involving native PGPB and AM Fungi to the plants. These native strains and AM Fungi increased accumulations of copper, iron, and zinc in wheat grains, enhanced grain yield, and soil fertility.

Keywords: AM Fungi, biofortification, PGPB, soil microbial enzymes

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Authors: Dimassi Wissem

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In this work, we investigate the effect of combination between the porous silicon (PS) layer passivized with Lithium Bromide (LiBr) and grooving of grain boundaries (GB) in multi crystalline silicon. The grain boundaries were grooved in order to reduce the area of these highly recombining regions. Using optimized conditions, grooved GB's enable deep phosphorus diffusion and deep metallic contacts. We have evaluated the effects of LiBr on the surface properties of porous silicon on the performance of silicon solar cells. The results show a significant improvement of the internal quantum efficiency, which is strongly related to the photo-generated current. We have also shown a reduction of the surface recombination velocity and an improvement of the diffusion length after the LiBr process. As a result, the I–V characteristics under the dark and AM1.5 illumination were improved. It was also observed a reduction of the GB recombination velocity, which was deduced from light-beam-induced-current (LBIC) measurements. Such grooving in multi crystalline silicon enables passivization of GB-related defects. These results are discussed and compared to solar cells based on untreated multi crystalline silicon wafers.

Keywords: Multicrystalline silicon, LiBr, porous silicon, passivation

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Authors: Bibek Sapkota, Michael Burton, Krishna Prasad Timsina

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This paper presents a discrete choice experiment (DCE)-based analysis of farmers' preferences for rice variety attributes involving 540 farmers from the Terai region of Nepal clustered into East, Mid, and Western Terai regions. Findings reveal that farmers prioritize grain yield, finer grain types, drought tolerance, and shorter crop duration when selecting rice varieties, with subtle gender-based differences observed. However, breeding programs have predominantly emphasized grain yield and crop duration, possibly neglecting other vital traits. Furthermore, the research reveals a concerning decline in the yield trends of both released and registered rice varieties. Notably, the limited availability of recommended rainfed varieties, despite strong farmer preferences for drought tolerance, underscores the imperative of bridging this gap to ensure food security. This study provides insights into the multifaceted nature of farmer preferences and calls for a more holistic approach to varietal development that aligns with farmers' needs and the evolving challenges of rice farming in the Terai region of Nepal.

Keywords: breeders’ preferences, discrete choice experiment, farmers’ preferences, rice variety attributes

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Authors: Nkwachukwu Chukwuchekwa, Joy Ulumma Chukwuchekwa

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Magnetic characteristics of grain-oriented electrical steel (GOES) are usually measured at high flux densities suitable for its typical applications in power transformers. There are limited magnetic data at low flux densities which are relevant for the characterization of GOES for applications in metering instrument transformers and low frequency magnetic shielding in magnetic resonance imaging medical scanners. Magnetic properties such as coercivity, B-H loop, AC relative permeability and specific power loss of conventional grain oriented (CGO) and high permeability grain oriented (HGO) electrical steels were measured and compared at high and low flux densities at power magnetising frequency. 40 strips comprising 20 CGO and 20 HGO, 305 mm x 30 mm x 0.27 mm from a supplier were tested. The HGO and CGO strips had average grain sizes of 9 mm and 4 mm respectively. Each strip was singly magnetised under sinusoidal peak flux density from 8.0 mT to 1.5 T at a magnetising frequency of 50 Hz. The novel single sheet tester comprises a personal computer in which LabVIEW version 8.5 from National Instruments (NI) was installed, a NI 4461 data acquisition (DAQ) card, an impedance matching transformer, to match the 600  minimum load impedance of the DAQ card with the 5 to 20  low impedance of the magnetising circuit, and a 4.7 Ω shunt resistor. A double vertical yoke made of GOES which is 290 mm long and 32 mm wide is used. A 500-turn secondary winding, about 80 mm in length, was wound around a plastic former, 270 mm x 40 mm, housing the sample, while a 100-turn primary winding, covering the entire length of the plastic former was wound over the secondary winding. A standard Epstein strip to be tested is placed between the yokes. The magnetising voltage was generated by the LabVIEW program through a voltage output from the DAQ card. The voltage drop across the shunt resistor and the secondary voltage were acquired by the card for calculation of magnetic field strength and flux density respectively. A feedback control system implemented in LabVIEW was used to control the flux density and to make the induced secondary voltage waveforms sinusoidal to have repeatable and comparable measurements. The low noise NI4461 card with 24 bit resolution and a sampling rate of 204.8 KHz and 92 KHz bandwidth were chosen to take the measurements to minimize the influence of thermal noise. In order to reduce environmental noise, the yokes, sample and search coil carrier were placed in a noise shielding chamber. HGO was found to have better magnetic properties at both high and low magnetisation regimes. This is because of the higher grain size of HGO and higher grain-grain misorientation of CGO. HGO is better CGO in both low and high magnetic field applications.

Keywords: flux density, electrical steel, LabVIEW, magnetization

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Authors: Ramadas Narayanan, Surya Bhattrai, Vu Hoan

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Threshing and cleaning are crucial post-harvest procedures that are carried out to separate the grain or seed from the harvested plant and eliminate any potential contaminants or foreign debris. After harvesting, threshing and cleaning are necessary for the clean seeds to guarantee high quality and acceptable for consumption or further processing. For mechanised production, threshing can be conducted in a thresher. Afterwards, the seeds are to be cleaned in dedicated seed-cleaning facilities. This research investigates the effectiveness of Kimseed cleaning equipment MK3, designed for grain crops for processing new crops such as sesame, fennel and kalonji. Subsequently, systematic trials were conducted to adapt the equipment to the applications in sesame and spice crops. It was done to develop methods for mechanising harvest and post-harvest operations. For sesame, it is recommended to have t a two-step process in the cleaning machine to remove large and small contaminants. The first step is to remove the large contaminants, and the second is to remove the smaller ones. The optimal parameters for cleaning fennel are a shaker frequency of 6.0 to 6.5 Hz and an airflow of 1.0 to 1.5 m/s. The optimal parameters for cleaning kalonji are a shaker frequency of 5.5Hz to 6.0 Hz and airflow of 1.0 to under 1.5m/s.

Keywords: sustainable mechanisation, sead cleaning process, optimal setting, shaker frequency

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Authors: Lawrence I. Onyeji, Girish M. Kale, M. Bijan Kermani

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Corrosion problem which exists in every stage of oil and gas production has been a great challenge to the operators in the industry. The conventional carbon steel with all its inherent advantages has been adjudged susceptible to the aggressive corrosion environment of oilfield. This has aroused increased interest in the use of micro alloyed steels for oil and gas production and transportation. The corrosion behavior of three commercially supplied micro alloyed steels designated as A, B, and C have been investigated with API 5L X65 as reference samples. Electrochemical corrosion tests were conducted in an unbuffered 3.5 wt% NaCl solution saturated with CO₂ at 30 ⁰C for 24 hours. Pre-corrosion analyses revealed that samples A, B and X65 consist of ferrite-pearlite microstructures but with different grain sizes, shapes and distribution whereas sample C has bainitic microstructure with dispersed acicular ferrites. The results of the electrochemical corrosion tests showed that within the experimental conditions, the corrosion rate of the samples can be ranked as CR_(A)< CR_(X65)< CR_(B)< CR_(C). These results are attributed to difference in microstructures of the samples as depicted by ASTM grain size number in accordance with ASTM E112-12 Standard and ferrite-pearlite volume fractions determined by ImageJ Fiji grain size analysis software.

Keywords: carbon dioxide corrosion, corrosion behaviour, micro-alloyed steel, microstructures

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Authors: Mitsuhiro Okayasu, Lele Yang, Koji Shimotsu

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The effects of microstructural characteristics on the mechanical and hydrogen embrittlement properties of 1,800MPa grade hot stamping carbon steel were investigated experimentally. The tensile strength increased with increasing the hot stamping temperature until around 921°C, but that decreased with increasing the temperature in more than 921°C due to the increment of the size of lath martensite and prior austenite. With the hot stamping process, internal strain was slightly created in the sample, which led to the slight increment of the hardness value although no clear change of the microstructural formation was detected. Severity of hydrogen embrittlement was investigated using the hot stamped carbon steels after the immersion in a hydrogen gas, and that was directly attributed to the infiltration of the hydrogen into their grain boundaries. The high strength carbon steel with tiny lath martensite microstructure could make severe hydrogen brittleness as the hydrogen was strongly penetrated in the grain boundaries in the hydrogen gas for a month. Because of weak embrittlement for the as-received carbon (ferrite and pearlite), hydrogen embrittlement is caused by the high internal strain and high dislocation density. The hydrogen embrittlement for carbon steel is attributed to amount of the hydrogen immersed in-between grain boundaries, which is caused by the dislocation density and internal strain.

Keywords: hydrogen embrittlement, hot stamping process, carbon steel, mechanical property

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Authors: Zainal Arifin, Mohammad Saeri

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The purpose of this study is to determine the efficiency of irrigation use on the growth and yield of two varieties of rice. Water management research on rainfed lowland rice was carried out in dry season (DS I) 2016 in an area of 10,000 m2 in Bunbarat Village, Rubaru Subdistrict, Sumenep Regency. The research was randomized block design factorial with 8 treatments and repeated 3 times, ie Factor I (varieties): (a) Inpago 9, and (b) Sidenuk; factor II (irrigation): (a) Alternate Wetting and Drying, (b) intermittent, (c) submerged, and (d) inundated. The results showed that dominant weed species such as purslane (Portulaca oleraceae L.) and barnyard grass (Echinochloa crusgalli) were mostly found in rice cultivation with Alternate Wetting and Drying, intermittent and submerged irrigation treatment, while the lowest was inundated irrigation. The use of Sidenuk variety with Alternate Wetting and Drying irrigation yielded 5.7 t/ha dry grain harvest (dgh) and was not significantly different from the inundated watering using the Sidenuk variety (6.2 t/ha dgh). With Alternate Wetting and Drying irrigation technique, water use is more efficient as much as 1,503 m3/ha so as to produce 1 kg of grain, it needs 459 liters of water compared to inundated irrigation (665 liters/kg of grain). Results of analysis of rice farming Sidenuk variety with Alternate Wetting and Drying irrigation has the highest B/C ratio (2.56) so that economically feasible.

Keywords: water management, varieties, rice, dry season, rainfed lowland

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Authors: A. I. Al-Bassam, A. M. El-Nggar

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Polycrystalline Cu In I-x GaxSe2 thin films have been fabricated. Some physical properties such as lattice parameters, crystal structure and microstructure of Cu In I-x GaxSe2 were determined using X-ray diffractometry and scanning electron microscopy. X-ray diffraction analysis showed that the films with x ≥ 0.5 have a chalcopyrite structure and the films with x ≤ 0.5 have a zinc blende structure. The lattice parameters were found to vary linearly with composition over a wide range from x = 0 to x =1.0. The variation of lattice parameters with composition was found to obey Vegard's law. The variation of the c/a with composition was also linear. The quality of a wide range of Cu In I-xGaxSe2 thin film absorbers from CuInSe to CuGaSe was evaluated by Photoluminescence (PL) measurements.

Keywords: grain size, polycrystalline, solar cells, lattice parameters

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Authors: Davood Barari Tari

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In order to investigate the correlation of rice traits in different nitrogen management methods by modeling programming, an experiment was laid out in rice paddy field in an experimental field at Caspian Coastal Sea region from 2013 to 2014. Variety used was Shiroudi as a high yielding variety. Nitrogen management was in two methods. Amount of nitrogen at four levels (30, 60, 90, and 120 Kg N ha-1 and control) and nitrogen-splitting at four levels (T1: 50% in base + 50% in maximum tillering stage, T2= 33.33% basal +33.33% in maximum tillering stage +33.33% in panicle initiation stage, T3=25% basal+37.5% in maximum tillering stage +37.5% in panicle initiation stage, T4: 25% in basal + 25% in maximum tillering stage + 50% in panicle initiation stage). Results showed that nitrogen traits, total grain number, filled spikelets, panicle number per m2 had a significant correlation with grain yield. Results related to calibrated and validation of rice model methods indicated that correlation between rice yield and yield components was accurate. The correlation between panicle length and grain yield was minimum. Physiological indices was simulated with low accuracy. According to results, investigation of the correlation between rice traits in physiological, morphological and phenological characters and yield by modeling and simulation methods are very useful.

Keywords: rice, physiology, modelling, simulation, yield traits

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Authors: E. Chakwizira, D. J. Moot, M. Andrews, E. Teixeira

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Partitioning of macro-nutrients in wheat (Triticum aestivum L.) plant organs have not been extensively studied, particularly for modern genotypes grown under contrasting N supply. Nutrient accumulation and partitioning of phosphorus, potassium, calcium, magnesium and sulphur (P, K, Ca, Mg and S) were determined for six wheat genotypes [12S2-2021, 12S3-3019, 13S3-2026, Discovery, Duchess and Reliance] grown with (200 kg/ha) or without (0 kg/ha) nitrogen (N), in a fully irrigated field experiment in 2017-18 season at Lincoln, New Zealand. Data were collected at three growth stages (GS): tillering (GS21), anthesis (GS60) and grain maturity (GS92). Grain yield varied with both N and genotype; from 6-7.5 t/ha for the 0 kg N/ha crops and 8.1-9.3 t/ha for the 200 kg N/ha treatments. Plant nutrient uptake at maturity responded to both N supply and genotype for all nutrients, except S which did not differ among the genotypes. For example, total P uptake averaged 13.5 (12.4-14.3) kg/ha for the 0 kg N/ha treatments and 17.8 (15.1-19.7) kg/ha when 200 kg N/ha was applied. Similarly, K uptake increased from an average of 23 (21.6-25.3) for the 0 kg N/ha treatments to 34.3 (32.4-40.8) kg/ha when 200 kg N/ha was applied. Similar trends were observed for Ca and Mg. The S content only responded to N supply but not to genotype, increasing from 7.9 kg/ha for the 0 kg N treatments to 12.8 kg/ha when 200 kg N was applied. Relative nutrient content at anthesis compared with those at maturity were 30% for P, 100% for both K and Ca and 34% of Mg. Sulphur content at anthesis decreased 29% with N supply and was highest for genotypes 12S2-2021 compared with the other five genotype. At grain maturity, the ratio of nutrients in grain to total plant nutrient, defined as the nutrient harvest index (NHI) varied with both N supply and genotype. Averaged across treatments, the NHI was 0.96 for P, 0.53 for K, 0.58 for Ca, 0.90 for Mg and 0.85 for S. These results suggest that Ca and K should be provided earlier in the season as there is limited or no uptake after anthesis. These results also show that Ca and K are important for structural functions, while P, Mg and S are remobilised to the grains and become important for quality.

Keywords: anthesis, genotype, nutrient harvests index, NHI, Triticum aestivum L.

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Authors: Nadine Raidl, Benjamin Kaufmann, Michael Hofstätter, Peter Supancic

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If polycrystalline ZnO is properly doped and sintered under very specific conditions, it shows unique electrical properties, which are indispensable for today’s electronic industries, where it is used as the number one overvoltage protection material. Under a critical voltage, the polycrystalline bulk exhibits high electrical resistance but becomes suddenly up to twelve magnitudes more conductive if this voltage limit is exceeded (i.e., varistor effect). It is known that these peerless properties have their origin in the grain boundaries of the material. Electric charge is accumulated in the boundaries, causing a depletion layer in their vicinity and forming potential barriers (so-called Double Schottky Barriers, or DSB) which are responsible for the highly non-linear conductivity. Since ZnO is a piezoelectric material, mechanical stresses induce polarisation charges that modify the DSB heights and as a result the global electrical characteristics (i.e., piezotronic effect). In this work, a finite element method was used to simulate emerging stresses on individual grains in the bulk. Besides, experimental efforts were made to testify a coherent model that could explain this influence. Electron back scattering diffraction was used to identify grain orientations. With the help of wet chemical etching, grain polarization was determined. Micro lock-in infrared thermography (MLIRT) was applied to detect current paths through the material, and a micro 4-point probes method system (M4PPS) was employed to investigate current-voltage characteristics between single grains. Bulk samples were tested under uniaxial pressure. It was found that the conductivity can increase by up to three orders of magnitude with increasing stress. Through in-situ MLIRT, it could be shown that this effect is caused by the activation of additional current paths in the material. Further, compressive tests were performed on miniaturized samples with grain paths containing solely one or two grain boundaries. The tests evinced both an increase of the conductivity, as observed for the bulk, as well as a decreased conductivity. This phenomenon has been predicted theoretically and can be explained by piezotronically induced surface charges that have an impact on the DSB at the grain boundaries. Depending on grain orientation and stress direction, DSB can be raised or lowered. Also, the experiments revealed that the conductivity within one single specimen can increase and decrease, depending on the current direction. This novel finding indicates the existence of asymmetric Double Schottky Barriers, which was furthermore proved by complementary methods. MLIRT studies showed that the intensity of heat generation within individual current paths is dependent on the direction of the stimulating current. M4PPS was used to study the relationship between the I-V characteristics of single grain boundaries and grain orientation and revealed asymmetric behavior for very specific orientation configurations. A new model for the Double Schottky Barrier, taking into account the natural asymmetry and explaining the experimental results, will be given.

Keywords: Asymmetric Double Schottky Barrier, piezotronic, varistor, zinc oxide

Procedia PDF Downloads 267

Authors: Muhammad Aown Sammar Raza, Salman Ahmad, Muhammad Farrukh Saleem, Muhammad Saqlain Zaheer, Rashid Iqbal, Imran Haider, Muhammad Usman Aslam, Muhammad Adnan Nazar

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One of the main negative effects of climate change is the increasing scarcity of water worldwide, especially for irrigation purpose. In order to ensure food security with less available water, there is a need to adopt easy and economic techniques. Two of the effective techniques are; use of ground covers and partial root zone drying (PRD). A field experiment was arranged to find out the most suitable mulch for PRD irrigation system in wheat. The experiment was comprised of two irrigation methods (I0 = irrigation on both sides of roots and I1= irrigation to only one side of the root as alternate irrigation) and four ground covers (M0= open ground without any cover, M1= black plastic cover, M2= wheat straw cover and M4= cotton sticks cover). More plant height, spike length, number of spikelets and number of grains were found in full irrigation treatment. While water use efficiency and grain nutrient (NPK) contents were more in PRD irrigation. All soil covers suppress the weeds and significantly influenced the yield attributes, final yield as well as the grain nutrient contents. However black plastic cover performed the best. It was concluded that joint use of both techniques was more effective for water conservation and increasing grain yield than their sole application and combination of PRD with black plastic mulch performed the best than other ground covers combination used in the experiment.

Keywords: ground covers, partial root zone drying, grain yield, quality traits, WUE, weed control efficiency

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Authors: S. Ghanaraja, Subrata Ray, S. K. Nath

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Particle reinforced Metal Matrix Composite (MMC) succeeds in synergizing the metallic matrix with ceramic particle reinforcements to result in improved strength, particularly at elevated temperatures, but adversely it affects the ductility of the matrix because of agglomeration and porosity. The present study investigates the outcome of tensile properties in a cast and hot forged composite reinforced simultaneously with coarse and fine particles. Nano-sized alumina particles have been generated by milling mixture of aluminum and manganese dioxide powders. Milled particles after drying are added to molten metal and the resulting slurry is cast. The microstructure of the composites shows good distribution of both the size categories of particles without significant clustering. The presence of nanoparticles along with coarser particles in a composite improves both strength and ductility considerably. Delay in debonding of coarser particles to higher stress is due to reduced mismatch in extension caused by increased strain hardening in presence of the nanoparticles. However, higher addition of powder mix beyond a limit results in deterioration of mechanical properties, possibly due to clustering of nanoparticles. The porosity in cast composite generally increases with the increasing addition of powder mix as observed during process and on forging it has got reduced. The base alloy and nanocomposites show improvement in flow stress which could be attributed to lowering of porosity and grain refinement as a consequence of forging.

Keywords: aluminium, alumina, nano-particle reinforced composites, porosity

Procedia PDF Downloads 248

Authors: Abdullah Kaymakci, Daniel M. Madyira, Ntokozo Nkwanyana

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The effect of metal transfer modes on mechanical properties of welded 3CR12 stainless steel were investigated. This was achieved by butt welding 10 mm thick plates of 3CR12 in different positions while varying the welding positions for different metal transfer modes. The ASME IX: 2010 (Welding and Brazing Qualifications) code was used as a basis for welding variables. The material and the thickness of the base metal were kept constant together with the filler metal, shielding gas and joint types. The effect of the metal transfer modes on the microstructure and the mechanical properties of the 3CR12 steel was then investigated as it was hypothesized that the change in welding positions will affect the transfer modes partly due to the effect of gravity. The microscopic examination revealed that the substrate was characterized by dual phase microstructure, that is, alpha phase and beta phase grain structures. Using the spectroscopic examination results and the ferritic factor calculation had shown that the microstructure was expected to be ferritic-martensitic during air cooling process. The tested tensile strength and Charpy impact energy were measured to be 498 MPa and 102 J which were in line with mechanical properties given in the material certificate. The heat input in the material was observed to be greater than 1 kJ/mm which is the limiting factor for grain growth during the welding process. Grain growths were observed in the heat affected zone of the welded materials. Ferritic-martensitic microstructure was observed in the microstructure during the microscopic examination. The grain growth altered the mechanical properties of the test material. Globular down hand had higher mechanical properties than spray down hand. Globular vertical up had better mechanical properties than globular vertical down.

Keywords: welding, metal transfer modes, stainless steel, microstructure, hardness, tensile strength

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Authors: Yohanes Chekol Malede

Abstract:

σ-phase has negative effects on the corrosion responses and the mechanical properties of steels. The growth of σ-phase in the austenite matrix of AISI 347H FG steel was simulated using DICTRA software using CALPHAD method. The simulation work included the influence of both volume diffusion and grain boundary diffusion. The simulation results showed a good agreement with the experimental findings. The simulation results revealed a Cr-depleted and a Ni-enriched σ-phase/austenite interface. Effects of temperature, grain size, and composition of alloying elements on the growth kinetics of σ-phase were assessed. The simulated results were fitted to the JMAK equation and a good correlation was obtained.

Keywords: AISI 347H FG austenitic steel, CALPHAD, sigma phase, microstructure evolution

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Authors: Nidhi Adhlakha, K. L. Yadav

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Three phase magnetoelectric (ME) composites (1-x)(0.7BiFeO3-0.3CoFe2O4)-xPbTiO3 (or equivalently written as (1-x)(0.7BFO-0.3CFO)-xPT) with x variations 0, 0.30, 0.35, 0.40, 0.45 and 1.0 were synthesized using hybrid processing route. The effects of PT addition on structural, multiferroic and optical properties have been subsequently investigated. A detailed Rietveld refinement analysis of X-ray diffraction patterns has been performed, which confirms the presence of structural phases of individual constituents in the composites. Field emission scanning electron microscopy (FESEM) images are taken for microstructural analysis and grain size determination. Transmission electron microscopy (TEM) analysis of 0.3CFO-0.7BFO reveals the average particle size to be lying in the window of 8-10 nm. The temperature dependent dielectric constant at various frequencies (1 kHz, 10 kHz, 50 kHz, 100 kHz and 500 kHz) has been studied and the dielectric study reveals that the increase of dielectric constant and decrease of average dielectric loss of composites with incorporation of PT content. The room temperature ferromagnetic behavior of composites is confirmed through the observation of Magnetization vs. Magnetic field (M-H) hysteresis loops. The variation of magnetization with temperature indicates the presence of spin glass behavior in composites. Magnetoelectric coupling is evidenced in the composites through the observation of the dependence of the dielectric constant on the magnetic field, and magnetodielectric response of 2.05 % is observed for 45 mol% addition of PT content. The fractional change of magnetic field induced dielectric constant can also be expressed as ∆ε_r~γM^2 and the value of γ is found to be ~1.08×10-2 (emu/g)-2 for composite with x=0.40. Fourier transformed infrared (FTIR) spectroscopy of samples is carried out to analyze various bonds formation in the composites.

Keywords: composite, X-ray diffraction, dielectric properties, optical properties

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