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Allowable Limit (allowable + limit)
Selected AbstractsProbabilistic seismic demand analysis of controlled steel moment-resisting frame structuresEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 12 2002Luciana R. Barroso Abstract This paper describes a proposed methodology, referred to as probabilistic seismic control analysis, for the development of probabilistic seismic demand curves for structures with supplemental control devices. The resulting curves may be used to determine the probability that any response measure, whether for a structure or control device, exceeds a pre-determined allowable limit. This procedure couples conventional probabilistic seismic hazard analysis with non-linear dynamic structural analyses to provide system specific information. This method is performed by evaluating the performance of specific controlled systems under seismic excitations using the SAC Phase II structures for the Los Angeles region, and three different control-systems: (i) base isolation; (ii) linear viscous brace dampers; and (iii) active tendon braces. The use of a probabilistic format allows for consideration of structural response over a range of seismic hazards. The resulting annual hazard curves provide a basis for comparison between the different control strategies. Results for these curves indicate that no single control strategy is the most effective at all hazard levels. For example, at low return periods the viscous system has the lowest drift demands. However, at higher return periods, the isolation system becomes the most effective strategy. Copyright © 2002 John Wiley & Sons, Ltd. [source] Fully stressed frame structures unobtainable by conventional design methodologyINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2001Keith M. Mueller Abstract A structure is said to be fully stressed if every member of the structure is stressed to its maximum allowable limit for at least one of the loading conditions. Fully stressed design is most commonly used for small and medium size frames where drift is not a primary concern. There are several potential methods available to the engineer to proportion a fully stressed frame structure. The most commonly used methods are those taught to all structural engineering students and are very easy to understand and to implement. These conventional methods are based on the intuitive idea that if a member is overstressed, it should be made larger. If a member is understressed, it can be made smaller, saving valuable material. It has been found that a large number of distinct fully stressed designs can exist for a single frame structure subjected to multiple loading conditions. This study will demonstrate that conventional methods are unable to converge to many, if not most, of these designs. These unobtainable designs are referred to as ,repellers' under the action of conventional methods. Other, more complicated methods can be used to locate these repelling fully stressed designs. For example, Newton's method can be used to solve a non-linear system of equations that defines the fully stressed state. However, Newton's method can be plagued by divergence and also by convergence to physically meaningless solutions. This study will propose a new fully stressed design technique that does not have these problems. Copyright © 2001 John Wiley & Sons, Ltd. [source] Age, growth, mortality and population structure of the oyster, Crassostrea madrasensis, in the Moheskhali Channel (southeastern coast of Bangladesh)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2008S. M. Nurul Amin Summary The population structure, age, growth, mortality and harvest intensity of the oyster Crassostrea madrasensis were examined in the Moheskhali Channel, Bangladesh between June 2003 and May 2004. The channel is a representative habitat for the area. C. madrasensis monthly length frequency data were analyzed using FiSAT software for estimating population parameters, including asymptotic length (L), growth co-efficient (K) and recruitment pattern to assess the status of the stock. Asymptotic length (L,) and growth co-efficient (K) were 20.88 cm and 0.35 year,1, respectively. The growth performance index (,,) was calculated with 2.18. The growth pattern showed negative allometric growth (b < 3), with an asymptotic weight (W) of about 1124.6 g. The oyster attained an average length of 6.17 cm at the end of 1 year. Total mortality (Z) by length-converted catch curve was estimated at 1.78 year,1, fishing mortality (F) at 0.77 year,1, and natural mortality (M) at 1.01 year,1. The exploitation level (E) of C. madrasensis was 0.43, while the maximum allowable limit of exploitation (Emax) was 0.45 for the highest yield. The recruitment pattern was continuous, displaying a single major peak event per year. Habitat temperatures were 25.5,31.0°C (mean ± SD, 29 ± 1.62°C); salinity range was from 12.36 to 26.0 ppt (mean ± SD, 19.6 ± 4.7 ppt). The exploitation level (0.43) indicated that the oyster stock was exploited at almost maximum yield in this channel. [source] DETERMINATION OF HISTAMINE AND BACTERIAL ISOLATION IN MARLIN FILLETS (MAKAIRA NIGRICANS) IMPLICATED IN A FOODBORNE POISONINGJOURNAL OF FOOD SAFETY, Issue 3 2010H.C. CHEN ABSTRACT An incident of foodborne poisoning causing illness in seven victims due to ingestion of marlin fillets occurred in August, 2008, in Kaohsiung City, southern Taiwan. The two suspected marlin samples contained 47.8 and 43.5 mg/100 g of histamine, which is greater than the 5.0 mg/100 g allowable limit suggested by the U.S. Food and Drug Administration. Given the allergy-like symptoms of the victims and the high histamine content in the suspected marlin samples, this foodborne poisoning was strongly suspected to be due to histamine intoxication. Two histamine-producing bacterial strains capable of producing 3.10 ppm and 4.20 ppm of histamine in trypticase soy broth (TSB) supplemented with 1.0% l -histidine (TSBH) were identified as Bacillus subtilis by 16S rDNA sequencing with polymerase chain reaction amplification. However, major histamine-forming bacteria might have been killed during the preparation of fillets before serving and these two B. subtilis isolates might not be the main contributors to histamine accumulation in suspected fillets. PRACTICAL APPLICATIONS Based on the finding that high contents of histamine (>40 mg/100 g) were detected in the suspected marlin samples, we speculate the temperature abuse of the fillets before cooking contributed to the presence of high histamine levels in marlin fillets and resulted in foodborne poisoning. Although two histamine-producing Bacillus subtilis strains were isolated from suspected fish samples, both might not to be the main contributors to histamine accumulation because of low histamine production. These results re-emphasize proper handling temperature for seafoods and offer an important awareness which Makaira nigricans fillets could become a hazardous food item in causing histamine poisoning even though no quality deficiency was observed on the fillets. [source] Dietary effects on growth, plasma lipid and tissues of rats fed with non-conventional oil of Telfairia occidentalisJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2004Ibironke A Ajayi Abstract The nutritional value of Telfairia occidentalis seed and seed oil available in local market was studied in rats. The average values of the proximate analysis on dry matter basis were 203 g kg,1 crude protein, 536.3 g kg,1 fat, 39 g kg,1 ash, 95 g kg,1 crude fibre and 43.7 g kg,1 carbohydrate, while the moisture content was 75 g kg,1. The mineral analyses showed that T occidentalis seeds contain potassium (3280 mg kg,1), sodium (1230 mg kg,1), magnesium (60.8 mg kg,1), calcium (60.8 mg kg,1) and iron (13.0 mg kg,1). The oil extracted from the seed sample showed physicochemical properties that suggest its suitability for edible and industrial uses. The oil contained high levels of unsaturated fatty acids, oleic and linoleic, which accounted for 63.22% of total fatty acids recovered, while palmitic acid (27.4% of the oil by weight) was the most prevalent saturated fatty acid in the oil. No trace of eleostearic acid was detected in the oil. The effect on physical appearance, weight gain, organ weight, tissue and plasma cholesterol and triacylglycerol levels was determined in rats fed a diet containing 5% T occidentalis oil. These were compared with those of rats fed a control diet (0% T occidentalis oil) over an 8 week study period. Weekly monitoring of the rats showed good physical appearance and steady weight increase. The test rats were not anaemic and no mortality was recorded. While there was a significantly higher (p < 0.05) level of cholesterol in the heart of test rats compared with the control, there was a significantly lower (p < 0.05) plasma cholesterol level, suggesting that T occidentalis seed oil can be used to lower plasma levels of cholesterol. Histological examination of the sections of the heart, liver, kidney and spleen of the test rats revealed varying degrees of pathology. These include artherosclerotic changes in the walls of vasa vasori and lymphatics in the heart and hyaline degeneration of myofibrils, fatty infiltration of hepatocytes, and glomerular and tubular degeneration in the kidneys. These lesions may have been due to the effect of fatty acids, especially erucic acid, in the seed oil, which at 1.24% (less that the 5% conventional allowable limit for edible oils) may be intolerable for rats and may be unsuitable for human consumption. The seed oil may be used for industrial purposes such as soap making, lubrication and cosmetics for which it is well suited. Copyright © 2004 Society of Chemical Industry [source] Sterilization of ginseng using a high pressure CO2 at moderate temperaturesBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009Fariba Dehghani Abstract The aim of this study was to determine the feasibility of using high pressure CO2 for sterilization of Ginseng powder, as an alternative method to conventional techniques such as ,-irradiation and ethylene oxide. The Ginseng sample used in this study was originally contaminated with fungi and 5,×,107 bacteria/g that was not suitable for oral use. This is the first time that high pressure CO2 has been used for the sterilization of herbal medicine to decrease the total aerobic microbial count (TAMC) and fungi. The effect of the process duration, operating pressure, temperature, and amount of additives on the sterilization efficiency of high pressure CO2 were investigated. The process duration was varied over 15 h; the pressure between 100 and 200 bar and the temperature between 25 and 75°C. A 2.67-log reduction of bacteria in the Ginseng sample was achieved after long treatment time of 15 h at 60°C and 100 bar, when using neat carbon dioxide. However, the addition of a small quantity of water/ethanol/H2O2 mixture, as low as 0.02 mL of each additive/g Ginseng powder, was sufficient for complete inactivation of fungi within 6 h at 60°C and 100 bar. At these conditions the bacterial count was decreased from 5,×,107 to 2.0,×,103 TAMC/g complying with the TGA standard for orally ingested products. A 4.3 log reduction in bacteria was achieved at 150 bar and 30°C, decreasing the TAMC in Ginseng sample to 2,000, below the allowable limit. However, fungi still remained in the sample. The complete inactivation of both bacteria and fungi was achieved within 2 h at 30°C and 170 bar using 0.1 mL of each additive/g Ginseng. Microbial inactivation at this low temperature opens an avenue for the sterilization of many thermally labile pharmaceutical and food products that may involve sensitive compounds to ,-radiation and chemically reactive antiseptic agents. Biotechnol. Bioeng. 2009;102: 569,576. © 2008 Wiley Periodicals, Inc. [source] Copper, zinc, and cadmium accumulation in two prairie soils and crops as influenced by repeated applications of manure,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2007Sarah L. Lipoth Abstract A study was conducted to determine the effect of repeated (5,7 y) annual application of liquid swine or solid cattle manure on the plant availability of copper (Cu), zinc (Zn), and cadmium (Cd) at two field sites in the W-central and E-central agricultural regions of Saskatchewan, Canada. Soil samples, plant-straw and grain samples from the 2003 growing season were collected and analyzed for total Cu, Zn, and Cd concentrations using nitric acid microwave digestion followed by atomic-absorption spectroscopy. An ammonium bicarbonate diethylenetriaminepentaacetic acid (AB-DTPA) extraction was performed on the soil samples as a measure of the plant-available fraction. Crop plants that were tested included wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). The results of this study indicated that long-term repeated applications of manure fertilizer sometimes resulted in increased plant availability of Cu, Zn, and Cd, as reflected in increased concentrations of the plant-available metal observed both in the soil and plant tissue. In the case of Cu and Zn, these increases were related to the rate of application, as the manure is a source of Cu and Zn. Changes in soil conditions from repeated manure application, including a decrease in pH and stimulated plant-root growth can explain the effect that both manure and urea-fertilizer application had on increasing the Cd concentration in the plant. Overall, there does not appear to be any concern about soil metal loading and plant accumulation in these soils after 5,7 y of manure application, as soil and plant concentrations were well below the allowable limits. [source] | ||||||||||||||||