Maximum Permissible Load Research Articles

External phosphorus load estimates and P-budget for the hydroelectric reservoir of Bort-Les-Orgues, France

This paper presents two methods used to estimate the externalphosphorus load for the hydroelectric reservoir ofBort-Les-Orgues (in France's `Massif Central' region). The Pload calculated from export coefficients (150 t yr-1) agreedwith field measurements taken during a one-year survey carriedout from March 1996 to February 1997 (121 t yr-1). Exportcoefficients represent a good option for estimating phosphorusloads of other reservoirs in the region of Bort-Les-Orgues,provided that they display similar characteristics. Theseexternal load estimates are greater than the maximum permissibleload for a mesotrophic lake calculated from the OECD equations(40 t yr-1); thus, a yearly reduction of about 60 t shouldideally be achieved. This target, however, is probably tooambitious, and measures to reduce both point and non-pointsources must be implemented for the reservoir to tbe mesotrophic.Moreover, Bort-Les-Orgues is a tourist area. As such, thepresence of algal blooms (a regular occurrence on the lake) dueto an excess of P in the lake's water inflow could actuallyexert a negative impact on regional economy.

Real-time contingency evaluation and ranking technique

The tendency towards maximising economic benefits has led power systems utilities to run close to the limits of stable operation. This has necessitated the study of the stressed situation of the power system network to accomplish efficient energy management without losing its reliability. On-line monitoring of power system stability has become a vital factor for electric utilities. An effective method for real-time monitoring of system status and thus voltage collapse prediction is described. The proposed technique investigates each line of the system through calculating an indicator that varies from 0 (no load condition) to 1 (maximum permissible loading condition). The basic concept of maximum power transfer through a line is utilised. The proposed contingency evaluation technique is applied on the IEEE 24 bus and IEEE 6 bus reliability test system and is found to be accurate in assessing the stressful status of the lines.

Developing human health-related chemical guidelines for reclaimed wastewater irrigation

We examined the methodology of developing globally applicable human health-related chemical guidelines of using wastewater for crop irrigation. Two approaches may be used to develop pollutant loading guidelines: (a) preventing pollutant accumulation in waste receiving soil and (b) maximizing soil's capacity to assimilate, attenuate, and detoxify harmful chemicals. Pollutant loading rates based on the first approach are in agreement with the fundamental principle of maintaining ecological balances in soil. But numerical limits usually are very stringent and it is difficult for communities to meet these requirements. Recommendations derived with the second approach represent the maximum permissible loadings beyond which pollutant levels in the soil may be harmful to the exposed population. A method employing the second approach was evaluated. Preliminary pollutant loading limits for land application of wastewater are derived by considering the food chain transfer of pollutants via intake of grain, vegetable, root/tuber, and fruit grown on wastewater-affected soils.

Developing human health-related chemical guidelines for reclaimed wastewater irrigation

We examined the methodology of developing globally applicable human health-related chemical guidelines using wastewater for crop irrigation. Two approaches may be used to develop pollutant loading. Guidelines: (a) preventing pollutant accumulation in waste receiving soil and (b) maximizing soil's capacity assimilate, attenuate, and detoxify harmful chemicals. Pollutant loading rates based on the first approach are in agreement with the fundamental principle of maintaining ecological balances in soil. But numerical limits usually are very stringent and it is difficult for communities to meet these requirements. Recommendations derived with the second approach represent the maximum permissible loadings beyond which pollutant levels in the soil may be harmful to the exposed population. A method employing the second approach was evaluated. Preliminary pollutant loading limits for land application of wastewater are derived by considering the food chain transfer of pollutants via intake of grain, vegetable, root/tuber, and it grown on wastewater-affected soils.

Characteristics of thin-wire shape memory actuators

Since 1987 a NiTi wire of only 0.156 mm diameter has been commercially available, which shows promising properties for medium force/ medium displacement actuators. The shape memory effects arise from a change from the martensitic to the austenitic phase at a conversion temperature of about 80 °C, causing forces of several newtons and a contraction of several percent. The current to reach this conversion temperature is about 300 mA over 2 s and the driving voltage is about 15 V per meter of wire. Our investigations on mechanical, electrical and thermal characteristics have revealed an interesting feedback feature: the momentary resistance is a measure of the momentary state of contraction. Thus, easily controlled actuators of minimum weight might be realized. The reproducible dynamic operational conditions are: isostatic contraction, 1 N/3.8% to 2.5 N/4%; isometric force, 1 to 4N. The results of the tensile tests are: tensile strength, 20 N; maximum permissible load, 7.5 N; Young's modulus 34 000 N/mm 2 (standard NiTi) and 17 000 N/mm 2 (trained NiTi). The resistivity is about 44 Ω/m, with a positive temperature coefficient below 47 °C of + 1.5 × 10 −3/°C and above 100 °C of + 0.34 × 10 −3/°C and a negative temperature coefficient of −11 × 10 −3/°C during contraction of a standard NiTi at a load of 1.5 N. Endurance tests proved a lifetime of 260 000 cycles at 0.1 Hz, 2 N and 3.5 % contraction with a pulse amplitude of 360 mA or 16 V/m.

Physiological assessment of work load during manual load carrying. (Under the conditions in which the load is suspended from one hand and both hands).

Assessments of heart rate, blood pressure, temperature and the feeling of fatigue in ten health young adult male subjects were examined during seven different load conditions in which the load was suspended from one or both hands. From the assessment, it was found that the heart rate, systolic blood pressure and subjective feeling of fatigue correlated closely with the work load. Results indicated that the maximum permissible load weight when the load was suspended from one hand was under 35% of the subject's body weight. Necessary rest time for overcoming fatigue under the condition of suspending the weight from one hand increased approximately 23% when the load weight was increased by 5%. The maximum permissible load weight when the load was suspended form both hands was under 40% of the subject's body weight. Necessary rest time for overcoming fatigue under the latter condition increased approximately 19% when the load weight was increased by 5%.

Maximum Load Lifting Capacity of Males and Females in Teamwork

The main objective of this study was to determine the maximum permissible load lifting capacity (MLCT) of males and females working in teams of two persons. On the average, the maximum capacity of the two-people teams for infrequent lifting of compact loads from floor to the bench height of 89 [cm] was about 105 Kg for young males, and 76 Kg for young females. The ratio between the maximum capacity for a team of two males versus two females, defined as (female/male x 100) was 69.6% (S.D.=11.06%) with a range from 49.1% to 88.0%. It was proposed that when lifting in teams of two people, the majority of population (95%) should not be required to handle more than 83 Kg for males and 63 Kg for females.

Agronomic Requirements for Soil Utilization in Liquid Waste Disposal Systems – The Case of Sitel

At SITEL – the integrated effluent treatment system of Pólo Petroquímico do Sul (South Petrochemical Complex), Triunfo, State of Rio Grande do Sul, Brazil – both the final effluent and the thickened excess activated sludge are disposed of on land. Thorough agronomic investigations made possible the identification of appropriate soils for receiving the wastes and the establishment of some design criteria. Profile depth, texture, infiltration rate, internal drainage, slope and availability of land covered with intact vegetation were the main factors considered in the election of areas for effluent disposal. For sludge application the following factors were taken into account: drainage, slope, chemical characteristics (mainly pH and Organic Matter), distance to the sludge loading point, suitability to agronomic management, ease of access, topography and presence of an adequate grass species (pangola grass). The results of the preliminary agronomic investigations are presented and discussed. Design assumptions are confronted with actual operational data. Comparisons are made with other reported situations. A discussion on the limitations, shortcomings and incompleteness of the available criteria and guidelines is included, with particular focus on CEC, Infiltration Rates, Maximum Permissible Loadings, Nitrogen and Organic Matter.

Estimation of maximum permissible loads to be carried by Indians of different ages.

Porters in different age groups, 20-29 yr, 30-39 yr, 40-49 yr and 50 yr and above, carried loads of 0,20,30,40,50 and 60 kg, within the range carried by them in their daily work, at a fixed speed of 5 km h−1, the average normal speed of walking with loads. The range of energy expenditure relative to measured maximum oxygen uptake ([Vdot]O2 max) suggests that the maximum permissible loads to be carried at 5kmh−1 by subjects in these age groups are 41,23,21 and 11 kg, respectively.

Recovery of plant amines with carboxylic ion-exchange substrates and their subsequent analysis by thin-layer chromatography

Two grades of carboxymethylcellulose (CMC) and five ion-exchange resins were compared for their effectiveness in recovering endogenous amines from plant extracts.If amine loss was to be limited to 10%, the H + and Na + forms of CMC could not be loaded with the solutes from more than 0.25 and 1.5 gram fresh weight 9gfw) tissue per ml bed volume respectively. The corresponding ionic forms of a typical resin, Amberlite CG-50, would tolerate loadings ca. 5 × higher than this. However, it was then necessary to use very slow flow-rtes (13 ml cm −2 h −1) for both applying and eluting the amines and, even so, they could not be quantitatively displaced from any resin tested, with the possible exception f Duolite C433. If the extract was acidic, maximum permissible loading were reduced by a factor of 3 to 20, depending on substrate and ionic form. The composition of the amine fraction was essentially the same whatever substrate was used for its recovery and whatever percentage of it had been lost.

Derating Cables in Trays Traversing Firestops or Wrapped in Fireproofing

Using ICEA Standard P-54-440 as the basis, this paper derives simple equations to calculate the maximum permissible load losses for cables in trays passing through firestops or covered with fireproofing material. From these loss values are deduced ampacity multiplying factors which when applied to the ICEA standard ampacities, provide the permissible ampere loading for the cables. A basic factor in the derivation is the use of previously published experimental data relating to the heating of cables in firestops to calculate the thermal conductance of the firestops.

A simple deflection model for agricultural tyres

A simple geometrical theory is presented for pneumatic tyre deflection under load on a smooth, rigid, plane surface. The model, in terms of dimensionless parameters, is then modified to a dimensional, empirical form suitable for fitting to experimental data relating load, inflation pressure and deflection; and relating maximum permissible load to inflation pressure and tyre geometry. Experimental results for agricultural tyres are used to show that the theoretically-based, empirical equations fit the data well. The model shows promise of being adaptable to study tyre behaviour in soil.

Danger of auditory impairment from impulse noise: A comparative study of the CHABA damage-risk criteria and those of the Federal Republic of Germany.

On the basis of the impulse diagrams of various weapons and many audiometric tests, the CHABA impulse-noise damage-risk criteria (DRC) are compared with those of the Federal Republic of Germany. Both DRC indicate maximum permissible exposures in terms of peak-pressure level and of effective duration. Both DRC aim to protect 95% of the exposed population from permanent auditory damage. The computation of the effective duration differs between the CHABA DRC and the German DRC, and it generally results in a longer effective duration for CHABA. The current study is based on the results for more than 10 000 soldiers, who were audiometrically tested in a mobile monitoring station before firing practice and beginning 2 min after exposure until complete recovery. In a special study, it was possible to compare the results for 478 German soldiers and to evaluate the relative value of the CHABA DRC and the German DRC. This comparison showed that the CHABA DRC are too restrictive, permitting unnecessary "less maximum permissible load" than the German DRC. Moreover, owing to the large variability in TTS2, measurement of the whole recovery time beginning 2 min after exposure has a greater predictive value. Therefore, recovery time should be used in the evaluation of the DRC.

Thermo‐mechanical load capacity and deformation onset of silicon wafers during the high‐temperature process

AbstractThe plastic deformations occurring during technological high‐temperature treatment of silicon wafers are discussed and are simulated experimentally by means of static loading. From the results obtained a critical stress‐time product is derived which can be used for a quantitative estimate of the maximum permissible load of the wafer during heating and cooling treatments in technological processes.

Adhesion Measurements of Metallizations for Hybrid Microcircuits

In a method developed for measuring the adhesion of metallic films for hybrid microelectronic circuits, pull rods soldered or epoxy bonded to metallization pads are pulled off at an angle normal to the substrate. The test circuits and testing devices are described. Tensile strengths of 40 to 80 N/mm2and 5 to 30 N/mm2are typical for thin-film circuits and thick-film circuits, respectively. The weakest point in the overall circuit configuration is determined. The information obtained indicates the maximum permissible mechanical loads to which the discrete devices of microelectronic circuits can be exposed and may also be evaluated for process optimization.

Conversion of naphtha raffinate by steam under pressure

1. The authors have studied the effect of pressure on low-temperature conversion (gasification) of naphtha raffinate in the range 1–31 atm. It has been found that the maximum permissible load with respect to naphtha during its gasification is a linear function of pressure. It is shown that, with increasing pressure during gasification of naphtha by steam, the hydrogen content of the converted gases greatly decreases, while the methane content increases. 2. A study was also made of the effect of temperature on conversion of naphtha raffinate (43–136°C fraction) by steam at 200–320°C. It is shown that the process rate can be increased by increasing the temperature. 3. A two-stage scheme of naphtha raffinate conversion for manufacture of hydrogen is proposed and validated.

Radiofrequency Heating of Rubber and Carbon Black Mixes

Abstract In conclusion, the simple model of a uniform array of spherical conducting particles of negligible size, when modified for a random distribution, enables predictions as to the maximum permissible loading of carbon black in a rubber/black mix that can be heated by dielectric heating without breakdown. The theory agrees qualitatively with the results of Gehman's theory of random filler dispersions. It is not possible to compare values given by the theory with experimental results, because there is no reliable data giving breakdown voltage figures for rubber/black mixes of known dispersion. However predictions given by the theory agree qualitatively with experiments.

A Correlation of End Wall Losses in Plane Compressor Cascades

Consideration of parameters suggested by the momentum integral equations has lead to a successful correlation relating (a) the change of the free stream component of the end wall boundary layer displacement thickness to chord ratio, and (b) a profile parameter as functions of free stream loading. For the range of investigation, both correlations were found to be insensitive to gap-chord ratio, camber, stagger, incidence, and airfoil shape. Maximum permissible loading limits for operation without excessive end wall loss are shown to decrease with increasing inlet displacement thickness to chord ratio.

Scuffing as a factor in the design of nylon gears

In meshing gears various phenomena have been observed, all of which can lead to a breakdown of the transmission. A number of these phenomena, such as tooth rupture, wear, pitting and scuffing, also occur in nylon gears. Scuffing in gears can be ascribed to local overheating caused by friction between the flanks of engaging teeth. BLOK has derived a formula by which an insight into the scuffing of nylon gears can be obtained. It appears that in some cases the melting point of nylon is exceeded. Blok's formula makes it possible to determine the maximum permissible load taking into account these scuffing phenomena and to indicate measures by which the permissible load may be increased. The circumstances under which the calculation of the permissible load of nylon gears should be based on tooth rupture or on scuffing can also be established.

Choice of average heat load at the fuel element surface in a pressurized-water reactor

A method of determining the maximum permissible average heat load at the fuel element surface in a pressurized-water reactor is proposed for a cosinusoidal distribution of heat release with respect to height and subcooling ≥10° C at the channel outlet.