A statistical algorithm for comparing mode shapes of vibration testing before and after damage in timbers   总被引：3，自引：0，他引：3  

Chuanshuang Hu  Muhammad T. Afzal 《Journal of Wood Science》2006,52(4):348-352

Instances of local damage in timber such as knots, decay, and cracks can be translated into a reduction of service life due to mechanical and environmental loadings. In wood construction, it is very important to evaluate the weakest location and to detect damage at the earliest possible stage to avoid future catastrophic failure. In this study, modal testing was used on wood beams to generate the first two mode shapes. A novel statistical algorithm was proposed to extract a damage indicator by computing mode shapes of vibration testing before and after damage in timbers. The different damage severities, damage locations, and damage counts were simulated by removing mass from intact beams to verify the algorithm. The results showed that the proposed statistical algorithm is effective and suitable for the designed damage scenarios. It is reliable for the detection and location of local damage of different severities, location, and number. The peak values of the damage indicators computed from the first two mode shapes were sensitive to different damage severities and locations. They were also reliable for the detection of multiple cases of damage.  相似文献   

Efficacy of entomopathogenic fungi,nematodes and spinetoram combinations for integrated management of Thrips tabaci     

Waqas Wakil  Sehrish Gulzar  Sean Michael Prager  Muhammad Usman Ghazanfar  David I Shapiro-Ilan 《Pest management science》2023,79(9):3227-3238

  相似文献   

The importance of alternative host plants as reservoirs of the cotton leaf hopper,Amrasca devastans,and its natural enemies     

Rabia Saeed  Muhammad Razaq  Ian C. W. Hardy 《Journal of pest science》2015,88(3):517-531

  相似文献   

Compost and P amendments for stimulating microorganisms and maize growth in a saline soil from Pakistan in comparison with a nonsaline soil from Germany     

Sher Muhammad  Torsten Müller  Rainer Georg Joergensen 《植物养料与土壤学杂志》2007,170(6):745-752

A 92 d greenhouse pot experiment with maize (Zea mays L.) was carried out with a strongly saline soil from Pakistan (P‐s) in comparison with a nonsaline soil from Germany (G‐s) similar in pH and texture. The aim was to evaluate salinity effects on the decomposition of compost and effects of compost and P amendments on (1) plant growth and (2) microbial‐biomass formation. The yield of maize shoot‐C and root‐C increased in both soils in the order nonamended control < +triple superphosphate (TSP) (A1) < +compost (A2) < +(compost + TSP) (A3) < +TSP‐enriched compost (A4). In comparison with the control, the highest yield in treatment A4 was nearly doubled on the G‐s, but was increased more than 8‐fold on the saline P‐s. Averaging the three compost treatments, 32% of the compost added was decomposed in the German soil and 36% in the Pakistani soil on the basis of the compost recovered as particulate organic matter. These data were roughly in agreement with the CO₂‐evolution data. This indicates that the decomposition of compost was not affected by salinity. Compost‐derived CO₂ was mainly evolved until day 32, the root‐derived CO₂ from day 74 until the end of the experiment. The addition of compost resulted in higher contents of microbial biomass C and biomass P, but also in that of NaHCO₃‐extractable P. These three properties were significantly interrelated (r = 0.64–0.85), but on a lower level of significance than the relationships between shoot‐C, root‐C, and NaHCO₃‐extractable P (r = 0.90–0.93). Applying compost enriched with TSP (incubation of compost and TSP for 24 h) provided considerably more P to plants and microorganisms than the separate addition of these two components. The results suggest that the role of the microbial biomass as a sink and source for available P deserves further attention.  相似文献   

Genetic variability in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) of Pakistan based on polymorphism for high molecular weight glutenin subunits     

Tayyaba Sultana  Abdul Ghafoor  Muhammad Ashraf 《Genetic Resources and Crop Evolution》2007,54(6):1159-1165

Variation in bread wheat including pre and post green revolutions varieties of Pakistan along with landraces was investigated for high molecular weight Glutenin subunits (HMW Gs) encoded at three genes (Glu-A1, Glu-B1, Glu-D1) with SDS-PAGE. The germplasm was diverse and unique on the basis of HMW Gs compositions and out of 14 alleles detected at all the Glu-1 loci, three belonged to Glu-A1, nine to Glu-B1 and two to Glu-D1 locus. High variation was observed in the landraces and higher gene diversity was observed between the populations as compared to the gene diversity within populations, whereas a reverse pattern of gene diversity was observed when populations were pooled across the region (higher within the regions than between the regions). A lack of relationship between the HMW Gs diversity and the altitude of collection site was observed. A data base has been generated in this study which could be expanded/exploited for cultivar development or management of gene bank.  相似文献   

Growth-related changes in wheat (Triticum aestivum L.) genotypes grown under salinity stress     

Muhammad Shahzad  Zulfiqar A. Saqib  Farhan Hafeez  Muhammad Bilal  Sabaz A. Khan  Saeed A. Asad 《Journal of plant nutrition》2016,39(9):1257-1265

The sensitivity of crop genotypes determines the level of growth reduction by salinity. Effect of salinity levels (7.5 and 15 dihydrate m^?1) using completely randomized design (CRD) with four replications per treatment were compared on germination, chlorophyll content, water potential, ionic sodium and potassium (Na⁺, K⁺) balance, and other growth-related parameters of six wheat genotypes for varietal differences under long-term salinity stress. Chlorophyll contents at flowering stage and yield aspects at maturity of all the wheat genotypes decreased with increasing salinity. The maximum Na⁺ concentration was observed at 7.5 and 15 dS m^?1 in Bhakhar and Saher-2000, respectively, while minimum Na⁺ concentration was observed for 9476. However, the maximum K⁺ concentration and water potential was noticed in 9476 at 7.5 dS m^?1. Careful selection of salt-tolerant genotypes for field crops is an important perspective especially in the developing countries facing salinity problem. Our results revealed that the wheat genotype 9476 performed best regarding growth and physiological parameters compared to other wheat genotypes.  相似文献   

Effect of Substrate Dependent Ethylene on Cotton (Gossypium hirsutum L.) at Physiological and Molecular Levels Under Salinity Stress     

Zulfiqar Ahmad  Shermeen Tahir  Abdul Rehman  Nabeel Khan Niazi  Muhammad Abid  Muhammad Amanullah 《Journal of plant nutrition》2015,38(12):1913-1928

The potential of encapsulated calcium carbide (ECC) in improving growth, yield and physiology of cotton under salinity was evaluated in pot experiment. Salinity was induced by sodium chloride (NaCl) at 0, 1250 and 2000 ppm. The ECC was applied at the rate of 0, 15, and 30 mg kg^?1 soil. The results revealed that ECC improved number of branches, yield, shoot dry biomass, root dry biomass, by 57, 67, 40, 22, and 18% respectively, over control. Similarly, net photosynthesis, stomatal conductance nitrogen, phosphorus and potassium (N, P and K) concentration of shoot were enhanced by 38, 34, 7, 25 and 11% over control, respectively. The induction of new set of proteins ranging from 11 to 26 kDa was also observed at various levels of ECC and salinity stress. These results proved the efficacy of very lower concentrations of ethylene produced by ECC and showed the behavior of different parameters of cotton to it under saline stress.  相似文献   

Combined Application of Potassium and Zinc Improves Water Relations,Stay Green,Irrigation Water Use Efficiency,and Grain Quality of Maize under Drought Stress     

Sajid Hussain  Muhammad Maqsood  Muhammad Ijaz  Abdul Sattar  Ahmad Sher 《Journal of plant nutrition》2020,43(14):2214-2225

Abstract

Maize (Zea mays L.) plays an important role in the global food security, but its production is threatened by climate change, especially drought stress. Potassium (K) and zinc (Zn) are considered useful to mitigate the negative consequences of drought stress in plants. Therefore, the objective of this two-year study was to identify the best combination of K and Zn application to improve the water relations, photosynthetic pigments, yield, irrigation water use efficiency (IWUE) and grain quality of maize sown under mild and severe drought stress conditions. The consisted of three drought stress levels viz. 1) well-watered as control (WW), 2) mild drought (MD) with 25?mm of potential soil moisture deficit (PSMD), 3) severe drought (SD) with 50?mm of PSMD and six K-Zn treatments: i.e. 125, 100 and 150?kg ha^?1 K with 0 and 12?kg ha^?1 Zn. The results indicated that K-Zn application improved the water relations and chlorophyll contents, biological yield and grain quality, irrespective of water stress treatment. The combined application of K-Zn under mild drought stress produced statistically same biological yield and grain quality as under well-irrigated without K-Zn fertilization and also produced compratively higher IWUE, biological yield and grain quality under sverer drought stress. Hence, the application of K at 150?kg ha^?1 in combination with Zn at 12?kg ha^?1 might be useful to improve the maize production and grain quality under drought stress. As IWUE was low in WW conditions, therefore, irrigation scheduling must be re-evaluated for optimum water use efficiency.  相似文献   

Mechanism and Degradation Pathways of Bisphenol A in Aqueous Solution by Strong Ionization Discharge     

Geng  Tingting  Yi  Chengwu  Yi  Rongjie  Yang  Liu  Nawaz  Muhammad Imran 《Water, air, and soil pollution》2020,231(4):1-11

The effects of anthropogenic noise have garnered significant attention in marine ecosystems, but comparatively less is known about its impacts on freshwater ecosystems. For fish that provide parental care, the effects of acoustic disturbance could have fitness-level consequences if nest tending behavior is altered. This study explored the effects of motorboat noise on the parental behavior of nesting male smallmouth bass (Micropterus dolomieu; Lacépède, 1802), an important freshwater game fish in North America that provides sole paternal care to offspring. Specifically, we evaluated how boat noise proximity to a bass nest (ranging from 4.5 to 90 m) influenced paternal care behaviors. A total of 73 fish were exposed to a 3-min motorboat playback designed to simulate a boat sound that typically occurs in areas near littoral nesting sites. The fish were video recorded, and their behaviors were analyzed before, during, and after exposure to the playback. Residency time was the only behavioral metric to be adversely affected by noise playbacks but only when in close proximity to the speaker. Our results suggest that boat noise may have an impact on bass reproductive fitness in specific contexts where combustion motors are used near shore during the nesting period. The largely null findings may indicate a resilience to boat noise and/or habituation to the noise. In addition, boats displace water and create waves that represent another form of disturbance that could be experienced by fish but was not simulated here. Future research should integrate behavioral and physiological responses to boat noise and other aspects of boat disturbance to better understand the fitness impacts of boating activity on freshwater fish.

  相似文献   

Partial substitution of chemical fertilizers with organic amendments increased rice yield by changing phosphorus fractions and improving phosphatase activities in fluvo-aquic soil     

Qaswar  Muhammad  Chai  Rushan  Ahmed  Waqas  Jing  Huang  Han  Tianfu  Liu  Kailou  Ye  Xinxin  Xu  Yongmei  Anthonio  Christian Kofi  Zhang  Huimin 《Journal of Soils and Sediments》2020,20(3):1285-1296

Journal of Soils and Sediments - The aim of this study was to investigate the effect of combined use of chemical fertilizers with wheat straw and swine manure on rice yield and&nbsp;phosphorus...  相似文献