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61.
Vahid Nasir 《Wood material science & engineering》2020,15(1):1-16
ABSTRACTSawing is the most common machining process and is present in both primary and secondary wood transformation sectors. The objective of this paper is to review how it is affected by different factors. The current challenges associated with various machining factors, process monitoring, and sensor selection were identified and explained. Consequently, four research challenges and technological gaps were outlined. (1) Contradictory results have been reported due to different cutting processes, wood species, measurement methods, and cutting speed range studied in literature, so special consideration needs to be taken when comparing results with those available in the literature. (2) Laboratory test conditions cannot yet fully represent the extreme cutting conditions in sawmills. More emphasis should be placed on those harsh industrial cutting conditions. (3) Research on wood cutting lacks multi-objective optimization approach, which suggests that sawdust generation should be simultaneously analysed with surface quality and power consumption. (4) Compared with metal cutting, little research has been conducted on wood sawing monitoring using an artificial intelligence approach, which should be prioritized in designing adaptive control systems. Combining intelligent monitoring and multi-objective optimization approaches should pave the way for controlling the sawing process so higher surface quality and cost efficient machining is achieved. 相似文献
62.
Shirvani E Lotfi M Kamalzadeh M Noaman V Bahriari M Morovati H Hatami A 《Tropical animal health and production》2012,44(1):191-195
Respiratory diseases in calves are responsible for major economic losses in both beef and dairy production. Several viruses,
such as bovine respiratory syncytial virus (BRSV), bovine herpes virus-1 (BoHV-1), bovine parainfluenza virus-3 (BPI-3V),
bovine viral diarrhea virus (BVDV), and bovine adenoviruses (BAV), are detected in most clinical cases with respiratory signs.
The aim of this study is to define seroprevalences of five major viral causes of bovine respiratory infections in cattle in
central region of Iran (Esfahan province). The population targeted was 642 dairy cows (Holstein–Friesian) from 25 farms. Samples
of blood serum from female cattle were examined. Sera were tested by commercial ELISA kits to detect antibody against BRSV,
BoHV-1, BPI-3V, BVDV, and BAV-3. The results were analyzed by Chi-square test. In the present study, seroprevalences of BRSV,
BoHV-1, PI3V, BVDV, and BAV-3 were 51.1%, 72%, 84.4%, 49.2%, and 55.6%, respectively. The present study shows that infections
of bovine respiratory viruses are very common in cattle in Esfahan. 相似文献
63.
The aim of this study was to evaluate the blood serum and diet concentrations of copper, zinc, and iron in Holstein dairy
cattle kept under semi-industrial farming in Isfahan province, central Iran. Moreover, the effects of season, pregnancy, and
daily milk yield on serum Cu, Zn, and Fe concentrations were also evaluated. The study was carried out on 12 semi-industrial
Holstein dairy cattle farms. A total of 120 blood serum samples (60 in each season) and 24 diet samples (12 in each season)
were collected in the summer and winter. The Cu, Fe, and Zn contents were assessed in samples using atomic absorption spectrophotometer.
In the summer, the mean concentrations of Cu and Fe in serum samples were lower and higher than the critical level, respectively
(P < 0.05). In total diet samples, the mean concentrations of Zn were significantly higher than critical level (P < 0.05). In summer, winter, and total diet samples, the mean concentrations of Fe were significantly higher than critical
level (P < 0.05). The serum Cu and Zn concentrations were significantly higher in the winter than those determined in the summer (P < 0.05). The serum Cu concentrations were significantly higher in nonpregnant than those in pregnant dairy cattle (P < 0.05). No significant difference was observed in serum Cu, Zn, and Fe concentrations of dairy cattle in different daily
milk yield groups. It can be concluded that Holstein dairy cattle reared under semi-industrial dairy farming were deficient
in serum Cu concentrations, especially in summer. Further, high level of Fe in blood serum might be due to feeding of cattle
with diet containing excess quantity of Fe. 相似文献
64.
Ebadi Arash Raja Omid Ebrahimian Hamed Yazdani Mohammad Reza Rezaverdinejad Vahid 《Paddy and Water Environment》2022,20(1):151-151
Paddy and Water Environment - 相似文献
65.
ABSTRACTThis paper investigates the effect of rotation speed and vibration response of a circular saw on the sawing process of Douglas-fir wood. An idling test was conducted on a guided circular saw to determine its stable operation speeds and vibration behavior. Short-time Fourier transform analysis was performed on saw idling test data, and variation of excited frequencies of the blade as a function of rotation speed was obtained. The saw blade critical speeds and the rotation speeds that correspond to saw flutter instability were identified. Then experimental cutting tests were conducted at different cutting conditions and the effect of rotation speed and saw vibration response on cutting power consumption and sawing accuracy was investigated. The results showed that conducting a saw idling test and vibration response analysis can identify the saw critical and flutter speeds, which is essential for identifying the optimum rotation speed of circular saw. There was a significant increase in power consumption when cutting at super-critical and super-flutter speed. The effect of rotation speed on sawing accuracy is complex and nonlinear. This effect interacts with feed speed, which makes it difficult to generalize sawing accuracy versus rotation speed in the circular sawing process. 相似文献
66.
Ramin Hosseinzadeh Javad Soosani Vahid Alijani Sheyda Khosravi Hamdieh Karimikia 《林业研究》2016,27(5):1137-1141
Topography is the most factor that has the greatest impact of all factor that affect the distribution.To study the diversity of trees and shrub species in the Perc forest situated in Khorramabad,Lorestan,140 circular plots of 1200 m~2 in a grid of 300 m 9 250 m were surveyed,using a systematic random sampling method.In each plot,the Margalef richness index,Shannon–Wiener diversity index,Hill's N_1 and Simpson indices and the evenness index of Simpson and Smith-Wilson were calculated and ordered on the basis of different classes of elevation,exposition and slope.The results indicated that slope did not have any significant effect on the indices.Exposition and elevation classes significant impacted the richness and diversity indices,but did not influence evenness.In general,the highest plant diversity was observed for slopes less than 15 %,northern aspects,without geographical direction,and elevations of 2100–2200 m.This information can be very useful in achieving the goals for sustainable management of forests.In addition to greater protection for regions with high diversity and reforestation(compatible species) in degraded area,we can help increase diversity in forests. 相似文献
67.
Asemi Z Jazayeri S Najafi M Samimi M Mofid V Shidfar F Foroushani AR Shahaboddin ME 《Pakistan journal of biological sciences: PJBS》2011,14(8):476-482
Previous studies have shown that inflammatory factors increases in pregnancy and is associated with several complications of pregnancy. The aim of this study was to assess effects of daily consumption of probiotic yoghurt on inflammatory factors in pregnant women. In a randomized clinical trial, seventy primigravid (the first pregnancy) and singleton pregnant women aged 18-30 years were assigned to two groups. Subjects consumed daily 200 g probiotic yoghurt containing Lactobacillus acidophilus La5 and Bifidobacterium animalis BB12 (10(7) CFU g(-1) for each) or 200 g conventional yoghurt for 9 weeks. Fasting blood samples were collected at baseline (28 weeks of gestation) and after intervention (37 weeks of gestation). Inflammatory factors, hs-CRP and TNF-alpha, were measured by Enzyme-linked Immunosorbent Assay (ELISA). Independent t-test was used to compare the two groups after intervention and paired-sample t-test compared variables before and after treatment. The results showed that the probiotic yogurt brought about a decrease in the serum hs-CRP level, from 10.44 +/- 1.56 to 7.44 +/- 1.03 microg mL(-1) (p = 0.041). There was no significant change in the conventional yogurt group in the serum hs-CRP level (12.55 +/- 1.57 to 14.51 +/- 1.62 microg mL(-1), p = 0.202). The probiotic yogurt had no effect on TNF-alpha (from 73.75 +/- 6.59 to 77.91 +/- 5.61 pg mL(-1), p = 0.633). Serum TNF-alpha did not change in the conventional yogurt group (p = 0.134). In conclusion probiotic yogurt significantly decreased hs-CRP in pregnant women but had no effect on TNF-alpha. 相似文献
68.
Hajar Eftekhari Babs Surujlal Vahid Shadparvar 《Journal Of Agricultural & Food Information》2013,14(4):274-289
The aim of this study was to identify rice supervising agents' educational needs in the field of multifunctional agriculture in Guilan Province, Iran. The statistical population included rice supervising agents in Guilan Province in 2014 (N = 169), of which 106 people were randomly sampled. The data collection tool was a research-designed questionnaire which was filled out by respondents using the self-reporting method. Results showed that among production functions of agriculture, rice supervising agents had a high need to be trained in the functions of “the production of raw material for rural handicrafts,” “the production of animal feed,” and “the production of medicinal herbs for medical and pharmaceutical purposes.” Participants' needs for training in nonproduction functions of agriculture were ranked by the Friedman test; results indicated a great need for education in the environmental functions of agriculture and a lesser need for education in its economic functions. 相似文献
69.
R. Shahriaripour A. Tajabadi Pour V. Mozaffari H. Dashti E. Adhami 《Journal of plant nutrition》2013,36(8):1166-1179
The effects of four salinity levels [0, 1000, 2000, and 3000 mg sodium chloride (NaCl) kg?1 soil] and three zinc (Zn) levels [0, 5, and 10 mg kg?1 soil as zinc sulfate (ZnSO4.7 H2O)] on growth and chemical composition of pistachio seedlings (Pistacia vera L.) cv. ‘Badami’ were studied in a calcareous soil under greenhouse conditions in a completely randomized design with three replications. After 26 weeks, the dry weights of leaves, stems and roots were measured and the total leaf area determined. Salinity decreased leaf, stem, and root dry weights and leaf area, while this effect diminished with increasing Zn levels. Zn fertilization increased leaf, stem and root Zn concentrations, leaf potassium (K) concentration, and stem and root sodium (Na) concentrations, while decreased leaf Na concentration, and stem and root K concentrations. Salinity stress decreased leaf, stem, and root Zn concentrations, and leaf K concentration, while salinity increased leaf, stem and root Na concentrations, and stem and root K concentrations. Proline accumulation increased with increasing salinity levels, whereas the reverse trend was observed for reducing sugar contents. Zn application decreased proline concentration but increased reducing sugar contents. These changes might have alleviated the adverse effects of salinity stress. 相似文献
70.
The Preparation of conductive biocomposite fiber through Carbon nanotubes (CNTs) incorporation into biopolymer matrixes has stimulated much interest for bio-implant applications. The present study focuses on development and characterization of biocomposite fiber composed of chitosan (CHT) as a biopolymer and multiwall carbon nanotubes (MWNTs) as a conductive filler. In term of processing, the most important challenge is to prepare a highly stable dispersion of MWNTs in biopolymer matrix. The hydrodynamic diameter distribution of CNTs in acetic acid solution acquired by dynamic light scattering (DLS).Results demonstrate the supreme stability of CNTs dispersion which is extremely essential for homogenous distribution of CNT in polymeric matrix. Rheological properties of the spinning solution have also been investigated to adjust the viscosity for fiber processing step. A range of viscosity between 2000–8000 cP, has been recorded in different CNT loading. The scanning electron microscopy (SEM) images of the surface and cross sectional area of the fibers reveal the formation of nano-pores after MWNT addition. The tensile strength show a maximum increase of about 33.65 % compared to bare CHT. Also, the measurement of four probe electrical conductivity for different MWNTs loading shows a maximum conductivity of 0.107 S/cm at percolation threshold of 2.89 wt%. 相似文献