959 resultados para MEASURING METHODS


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Dominance measuring methods are an approach for dealing with complex decision-making problems with imprecise information within multi-attribute value/utility theory. These methods are based on the computation of pairwise dominance values and exploit the information in the dominance matrix in different ways to derive measures of dominance intensity and rank the alternatives under consideration. In this paper we review dominance measuring methods proposed in the literature for dealing with imprecise information (intervals, ordinal information or fuzzy numbers) about decision-makers? preferences and their performance in comparison with other existing approaches, like SMAA and SMAA-II or Sarabando and Dias? method.

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In multi-attribute utility theory, it is often not easy to elicit precise values for the scaling weights representing the relative importance of criteria. A very widespread approach is to gather incomplete information. A recent approach for dealing with such situations is to use information about each alternative?s intensity of dominance, known as dominance measuring methods. Different dominancemeasuring methods have been proposed, and simulation studies have been carried out to compare these methods with each other and with other approaches but only when ordinal information about weights is available. In this paper, we useMonte Carlo simulation techniques to analyse the performance of and adapt such methods to deal with weight intervals, weights fitting independent normal probability distributions orweights represented by fuzzy numbers.Moreover, dominance measuringmethod performance is also compared with a widely used methodology dealing with incomplete information on weights, the stochastic multicriteria acceptability analysis (SMAA). SMAA is based on exploring the weight space to describe the evaluations that would make each alternative the preferred one.

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The temporal passage of fruit through the supply chain and the selection of consumable fruit by shoppers depend primarily upon fruit firmness. Traditionally, fruit firmness measuring methods, like Effegi and conical probes, are relatively inefficient and destructive. Simple, accurate and non-damaging methods of measuring fruit firmness are ideally required to help assure eating quality to the consumer without fruit wastage. The firmness of 'Hass' avocado fruit at a range of ripening stages was measured with the various different firmness measuring techniques of the Sinclair iQ Firmness Tester (SIQFT), the Electronic Firmometer (EF), the Analogue Firmness Meter (AFM) and hand squeezing. Measurements were made by each method at different points on the same fruit. Destructive bruise assessment was performed 48 h later, thereby allowing sufficient time for fruit to express any bruising resulting from the act of firmness measurements. Non-linear relationships were determined between fruit firmness values measured with the different techniques. The adjusted R2 for the relationship between the SIQFT and the EF was 91.6%. For the SIQFT and the AFM, the adjusted R2 was 73.7%. It was 77.7% for the SIQFT and hand squeezing. A significantly (P<0.05) high incidence of bruising was associated with firmness assessment by the EF as compared with either the SIQFT or the AFM. Among the methods compared, the SIQFT was non-damaging compared with the EF and relatively efficient for measuring the firmness. This instrument merits consideration as a quality control tool of choice in 'Hass' avocado supply chains.

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Axial shortening in vertical load bearing elements of reinforced concrete high-rise buildings is caused by the time dependent effects of shrinkage, creep and elastic shortening of concrete under loads. Such phenomenon has to be predicted at design stage and then updated during and after construction of the buildings in order to provide mitigation against the adverse effects of differential axial shortening among the elements. Existing measuring methods for updating previous predictions of axial shortening pose problems. With this in mind, a innovative procedure with a vibration based parameter called axial shortening index is proposed to update axial shortening of vertical elements based on variations in vibration characteristics of the buildings. This paper presents the development of the procedure and illustrates it through a numerical example of an unsymmetrical high-rise building with two outrigger and belt systems. Results indicate that the method has the capability to capture influence of different tributary areas, shear walls of outrigger and belt systems as well as the geometric complexity of the building.

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Research on carbon uptake in boreal forests has mainly focused on mature trees, even though ground vegetation species are effective assimilators and can substantially contribute to the CO2 uptake of forests. Here, I examine the photosynthesis of the most common species of ground vegetation in a series of differently aged Scots pine stands, and at two clear-cut sites with substantial differences in fertility. In general, the biomass of evergreen species was highest at poor sites and below canopies, whereas grasses and herbs predominated at fertile sites and open areas. Unlike mosses, the measured vascular species showed clear annual cycles in their photosynthetic activity, which increased earlier and decreased later in evergreen vascular species than in deciduous species. However, intraspecific variation and self-shading create differences in the overall level of photosynthesis. Light, temperature history, soil moisture and recent possible frosts could explain the changes in photosynthesis of low shrubs and partially also some changes in deciduous species. Light and the occurrence of rain events explained most of the variation in the photosynthesis of mosses. The photosynthetic production of ground vegetation was first upscaled, using species-specific and mass-based photosynthetic activities and average biomass of the site, and then integrated over the growing season, using changes in environmental factors. Leaf mass-based photosynthesis was highest in deciduous species, resulting in notably higher photosynthetic production at fertile sites than at poor clear-cut sites. The photosynthetic production decreased with stand age, because flora changed towards evergreen species, and light levels diminished below the canopy. In addition, the leaf mass-based photosynthetic activity of some low shrubs declined with the age of the surrounding trees. Different measuring methods led to different momentary rate of photosynthesis. Therefore, the choice of measuring method needs special attention.

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O objetivo deste estudo foi comparar os resultados da microinfiltração marginal obtidos por diferentes meios de aquisição de imagens e métodos de mensuração da penetração de prata em restaurações de resina composta classe V, in vitro. Dezoito pré-molares humanos hígidos, recém extraídos, foram divididos em três grupos, de acordo com o tipo de instrumento para preparação cavitária utilizado. Grupo 1: ponta diamantada número 3100, em alta rotação. Grupo 2: broca carbide número 330, em alta rotação. Grupo 3: ponta CVDentus código 82137, em aparelho de ultrassom. Foram realizados preparos cavitários padronizados (3x4x2mm) classe V nas faces vestibular e lingual de todos os dentes, com margens oclusais em esmalte e cervicais em dentina/cemento. As cavidades foram restauradas com o sistema adesivo Solobond M (VOCO) e resina composta Grandio (VOCO), a qual foi inserida e fotoativada em três incrementos. Os corpos de prova ficaram imersos em água destilada por 24h a 37oC; receberam acabamento e polimento com discos SofLex (3M) e foram novamente armazenados em água destilada, por sete dias. Posteriormente, as superfícies dentárias foram coberta com duas camadas de esmalte para unhas vermelho, exceto as áreas adjacentes às restaurações. Os espécimes ficaram imersos em solução aquosa de nitrato de prata a 50% por 24h e em solução fotorreveladora por 2h e foram seccionados no sentido vestíbulo-lingual, passando pelo centro das restaurações, com disco diamantado em baixa rotação. As amostras foram polidas em politriz horizontal e analisadas por diferentes métodos. À extensão da microinfiltração foi atribuído escores de 0 a 3 através de análises por meio de estereomicroscópio tradicional e com leds e microscópio ótico. As imagens obtidas na lupa com leds e no microscópio ótico tiveram as áreas infiltradas medidas através do software AxioVision. O teste χ2 de McNemar-Bowker revelou concordância estatística entre estereomicroscópio tradicional e o com leds (p=0,809) durante análises semiquantitativas. Porém, houve diferenças significantes entre microscópio ótico e estereomicroscópios (p<0,001). Houve boa correlação entre análises semiquantitativas e quantitativas de acordo com o teste de Spearmann (p<0,001). O teste de Kruskall-Wallis não revelou diferenças estatisticamente significantes (p=0,174) entre os grupos experimentais na análise quantitativa por microscópio ótico, em esmalte. Ao contrário do que se observa com a mesma em lupa (p<0,001). Conclui-se que o método de atribuição de escores comumente aplicado com a lupa nos estudos da microinfiltração marginal é uma opção confiável para análise da microinfiltração.

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地上净初级生产力(ANPP)是陆地生态系统碳循环的重要组成部分,但由于估测ANPP的方法不同使得对ANPP的估测值存在很大的不确定性。本文采用3种方法(群落中所有种群当年最大地上生物量之和(ANPPC1)、当年群落最大地上生物量(ANPPC2)以及每年固定日期(8月30日)的地上生物量(ANPPC3))在种群、功能群和群落水平上分别对连续19年(1980~1998)的内蒙古羊草和大针茅草原生态系统功能(如ANPP、植物多样性和水分利用效率(WUE))的动态变化进行了比较分析,同时探讨了不同估测方法下气候和放牧对ANPP的影响,在此基础上利用DNDC模型进行了ANPP的模拟和敏感性分析研究,主要结果包括: 在羊草和大针茅草原群落中,不同主要植物种群或功能群多年平均地上最大生物量出现的时间不同,而同一植物种群或功能群的年地上最大生物量出现的时间存在年际间的变化。采用当年最大地上生物量和8月30日固定日期的地上生物量作为群落ANPP的这两种方法高估了建群种或禾草功能群在群落中的作用。 羊草草原群落多年平均ANPPC1、ANPPC2和 ANPPC3分别是257.5、190.1和166.0 g.m-2;相应的大针茅草原多年平均ANPPC1、ANPPC2和 ANPPC3分别是180.4、132.8和122.5 g.m-2。就群落生产力而言,后两种常用的方法二和方法三分别低估了草原群落ANPP 14.2%~40.0%和15.5~59.0%。本文研究表明尽管ANPPC1与ANPPC2和ANPPC3之间存在显著的差异,但二者之间存在极显著的相关性:羊草草原的ANPPC1= 59.587+1.061×ANPPC2(r2=0.865, p<0.001),ANPPC1= 92.329+1.017×ANPPC3(r2=0.569, p<0.001);大针茅草原的ANPPC1= 32.918+1.114×ANPPC2(r2=0.814, p<0.001),ANPPC1= 76.120+0.875×ANPPC3(r2=0.499, p=0.001)。 种群、功能群和群落地上净初级生产力与气候因子间的关系因不同的估测方法而异。羊草草原的建群种羊草种群仅ANPPS3与8月和11月份的平均温度间存在显著相关性,而大针茅草原群落的建群种大针茅种群的ANPPS1和ANPPS2与3月份平均最高气温间呈负相关关系。在羊草草原群落,杂类草功能群ANPPF1和ANPPF2与3月份气温呈负相关关系;而灌木半灌木功能群ANPPF1和ANPPF2与3月份降水呈负相关关系。在大针茅草原群落,禾草功能群ANPPF1与5月份最高平均气温呈显著负相关关系。羊草草原群落ANPPC1和ANPPC3分别与11月份最低温度和平均温度存在显著负相关关系;大针茅草原群落ANPPC1与2和6月份月降水量间相关性显著,ANPP2与5月和11月份月平均最低温度呈显著负相关关系,而4~9月份,1和4月份平均最低温度对群落ANPPC3起决定作用。 在羊草和大针茅草原群落,由方法一得到的群落水分利用效率、Shannon植物多样性指数和均匀度指数与方法二或方法三得到的相应的指数间存在显著的差异,方法二和方法三得到的值间差异不显著。群落地上净初级生产力与相应估测方法的植物Shannon多样性指数和均匀度指数之间相关性不显著。 放牧条件下羊草或大针茅草原群落中的建群种羊草和大针茅在群落中的相对地上生物量较围栏内的相应植物种群的降低,而糙隐子草种群在群落中的比例上升。不同的放牧管理条件下,群落中植物种群地上现存量的季节动态发生变化。群落的植物组成及植物种群地上生物量在群落中总生物量的比例发生了明显的变化。利用遥感来估测地上净初级生产力时,分别低估了羊草和大针茅草原ANPP 52%和27%。 DNDC模型可以很好地模拟内蒙古典型草原生态系统的地上生物量,通过敏感性分析表明降水是草原植物生长的主要限制因子,在降水量增加或降低至日降水的30%时,模拟的地上生物量显著地高于或低于实测地上生物量值。在多年平均降水量为347mm的情况下,随着土壤粘粒含量的增加,地上生物量逐渐降低,与北美草原一致。

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A biosensor based on an H+ ion sensitive field effect transistor (H+-ISFET) and penicillin G acylase has been developed. The response time of the sensor to different concentrations of penicillin G was 30 s. In a 20 mM phosphate buffer at pH 7.0, the linear range of the calibration curve was from 0.5 to 8 mM. The coefficients of variation for three samples with 20 repeated measurements were below 5%. Stability of the sensor could reach about 6 months and more than 1000 runs were performed without a significant decrease of the output value. The sensor was tested for measurement of the penicillin G content in penicillin fermentation broth. Forty samples with low and high concentrations of penicillin G were chosen for the correlation test. The values assayed by the sensor method were compared with the values assayed by HPLC method, the correlation coefficient (r) was 0.9944 and the regression equation was y = 1.034X - 2083.7 respectively. The different measuring methods are discussed in the text. (C) 1998 Published by Elsevier Science S.A. All rights reserved.

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An experimental research was carried out to study the fluid mechanics of underwater supersonic gas jets. High pressure air was injected into a water tank through converging-diverging nozzles (Laval nozzles). The jets were operated at different conditions of over-, full-and under-expansions. The jet sequences were visualized using a CCD camera. It was found that the injection of supersonic air jets into water is always accompanied by strong flow oscillation, which is related to the phenomenon of shock waves feedback in the gas phase. The shock wave feedback is different from the acoustic feedback when a supersonic gas jet discharges into open air, which causes screech tone. It is a process that the shock waves enclosed in the gas pocket induce a periodic pressure with large amplitude variation in the gas jet. Consequently, the periodic pressure causes the jet oscillation including the large amplitude expansion. Detailed pressure measurements were also conducted to verify the shock wave feedback phenomenon. Three kinds of measuring methods were used, i.e., pressure probe submerged in water, pressure measurements from the side and front walls of the nozzle devices respectively. The results measured by these methods are in a good agreement. They show that every oscillation of the jets causes a sudden increase of pressure and the average frequency of the shock wave feedback is about 5-10 Hz.

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提出了一种平面自由运动半物理仿真系统的设计,对系统仿真试验的初始条件形成过程进行了具体阐述。系统中应用了一种平面两自由度直角坐标运动装置,用于完成系统驱动及速度和位置控制,同时这种运动装置能够进行直角坐标跟随运动,并与其末端测量机构共同实现对平面自由运动物体的高精度大范围位姿测量。建立了系统的运动学模型,并设计相应的控制算法实现试验所需的运动过程,采用半闭环和闭环相结合的方法有效控制系统的末端累积误差;针对提出的复合测量方法,建立了测量原理的数学模型,并进行了精度分析和仿真计算。实验证明这种设计和相应的控制测量方法合理可行。

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利用高精度三坐标测量机扫描功能,充分获得焊接板材端面线性三维数据坐标值,采用基于最小二乘法而建立的理想直线数学模型来评定直线度误差,并与实际采用塞尺法进行对比,结果发现采用三坐标测量更能详尽地反应整个焊接边缘直线度真实情况,节省大量的数据处理时间,且数据更加准确可靠,并在实际激光焊接中获得良好激光焊缝,同时直观地给出了焊接板材边缘线性特征,为剪板机刀具调整提供了方向与位置。

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As we all know, rock-like materials will absolutely show very different mechanical properties under the compressive stress and tensile stress respectively. Similarly, under the dynamic compressive stress or dynamic tensile stress, the characteristics of the dynamics showed by the rock-like materials also have great differences from the mechanical behavior under static force. Studying their similarities and differences in rock mechanics theory and practical engineering will be of great significance. Generally, there are compression modulus of elasticity and tensile modulus of elasticity corresponding to compressive stress state and the tensile stress state in the rock. Both the two kinds of elastic modulus play an extremely important role in calculation of engineering mechanics. Their reliability directly affects the accuracy and reliability of the calculation results of internal stress field and displacement field of engineering rock mass. At present, it is easy to obtain the compression modulus of elasticity in laboratory; but it is very difficult to determine the tensile modulus of elasticity with direct tensile test due to that direct tensile test is difficult to perform in laboratory in general. In order to solve this problem, this thesis invents and develops several indirect test methods to determine the static or dynamic tensile modulus of elasticity of rock-type materials with high reliability and good interoperability. For the static tensile modulus of elasticity, the analytical stress field solution has been given out for the Brazilian disc under the radial and linear concentration load with Airy stress function method. At the same time, the stress field has been modeled for the Brazilian disc test by using the finite element software of ANSYS and ADINA. The analytical stress field solution is verified to be right by comparatively researching the analytical stress field solution and the numerical stress field solution. Based on the analytical stress field solution, this thesis proposes that a strain gauge is pasted at the Brazilian disc center along the direction perpendicular to the applied force to indirectly determine the static tensile modulus of elasticity, and related measurement theory also has been developed. The method proposed here has good feasibility and high accuracy verified by the experimental results. For the dynamic tensile modulus of elasticity, two measuring methods and theories are invented here. The first one is that the Split Hopkinson Pressure Bar is used to attract the Brazilian disc to generate the dynamic load, make the dynamic tensile stress is formed at the Brazilian disc center; and also a strain gauge is pasted at the Brazilian disc center to record the deformation. The second is that, in the Hopkinson effect phenomenon, the reflection tensile stress wave is formed when the shock wave propagates to the free end of cylindrical rock bar and reflect, which can make the rock bar is under dynamic tensile stress state; and some strain gauges are pasted at the appropriate place on the rock bar to record the strain coursed by the tensile or compressive stress wave. At last, the dynamic tensile modulus of elasticity can be determined by the recorded strain and the dynamic tensile stress which can be determined by related theories developed in this thesis.

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Using knowledge of geology, geochemistry, coal petrology, mineralogy, by means of a variety of advanced measuring methods such as inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled atomic emission spectrometry (ICP-AES), X-ray powder diffraction (XRD), scanning electron microscopy with energy-dispersive spectrometer(SEM-EDS), sequential chemical extract and density fractions, the characteristics of trace elements and minerals in Jurassic Beipiao coal mine under inland limnetic sedimentary environment and in late Permian Jianxin and Qiaotou coal mines under paralic swamp sedimentary environment were studied. Compared with the average concentration in the world bituminous coals, the Beipiao coal was characterized by relatively high contents of Sc, Ti, Cr, Co, Ni, Zn, Se, Sr, Zr, Y, Ba, REE and Th, and lower contents of V, Rb, Cd, Sn, Pb, Bi and U; while the Jianxin coal was relatively enriched in Li, Sc, Ga, Sr, Y, Nb, Sb, Th and U, with low concentration of Be, Co, Ni, Cu, Ge, Zr, Mo, Cd, Cs, Ba, Pb and Bi; and the Qiaotou coal was enriched in Li, Sc, Sr, Nb, Ta, Zr, REE, Hf, Th and U, with low concentration of Be, V, Co, Ni, Cu, Ge, Mo, Cd, Cs, Ba, Tl, Pb and Bi. The concentrations of Ca, Mg and K in Beipiao coal are higher than those in Jianxin coal and Qiaotou coal, while Fe, S and Ti in Beipiao coal are lower than those in Jianxin coal and Qiaotou coal. The proximate analysis of coal samples was carried out, which indicated that Beipiao coal was medium- to high- ash (5.92-60.68%) with low sulphur coal, and Jianxin coal and Qiaotou coal was medium to high ash (8.85-46.33%) with high sulphur. The reflectivity was measured, which explained that Beipiao coal belonged to high volatile bituminous coal, Jianxin coal was low volatile bituminous coal and Qiaotou coal was low volatile anthracite. Quantitative maceral analyses were studied. The characteristics of rare earth elements (REE) were investigated, which showed that the total contents of REE were higher than that of the world's average content. With the increase of coal's metamorphic grade, the total contents of REE decreased from 98.5 X 10"6 of Beipiao coal to 94.2 X 10"6 of Jianxin coal, and to 75.9 X 10"6 of Qiaotou coal, and 5Eu reduced which indicated that the element Eu depleted. The characteristics of REE was controlled by the metamorphic grade of coal. And REE were mainly absorbed in clay minerals in Beipiao coal samples, while in Jianxin and Qiaotou coal mines, REE were primarily related to clay mineral and pyrite. The variation of trace elements in vertical direction of coal seams was studied, and the results showed that different trace elements differed greatly. The correlation between trace elements and ash were determined. Four major trace elements (aluminium-silicates, sulphide, carbonate and phosphate) accounted for the occurrence and distribution of most elements studied were determined. Coal samples were separated by density fraction, which showed that Cr, Cu, Mo and Pb were closely related to inorganic matters mainly distributed in P >2.6 and dropped remarkably in the density fractions P <2.3 . The occurrences of Co, Cr, Ni, As, Se, Mo, U were studied directly and quantitatively using sequential chemical extract with six steps, which showed that Co. Ni, Mo and U were mainly in the form of mineral, and As, Se chiefly in the form of organic state, while Cr mostly in the form of organic state and mineral. Major mineral phases presented in the Beipiao coal were Kaolinite, illite, quartz, calcite, and small amount of siderite, barite. While major mineral phases in Jianxin and Qiaotou coal were pyrite, kaolinite, and small amount of marcasite, rutile, sphalerite. This is the first time that the chromite in the coal was discovered in China, which indicates that Cr occurrence appeared in the form of chromite. The ratio of Sr/Ba, Sr/Ca and V/Ni in Beipiao coal mine under inland limnetic is smaller than that of in Jianxin and Qiaotou coal mines under paralic swamp. The ratio of K/Na and Th/U of Beipiao coal mine is higher than that of Jianxin and Qiaotou coal mine, which proved that Beipiao coal was not affected by sea water and Jianxin and Qiaotou coal were affected by sea water. Trace elements such as Cr, Ni, Mo in minerals were analyzed by SEM-EDS. The factors controlling the enrichment of trace elements can be divided into syngenetic stage factors and epigenetic stage factors.

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Available methods for measuring the impact of ocean acidification (OA) and leakage from carbon capture and storage (CCS) on marine sedimentary pH profiles are unsuitable for replicated experimental setups. To overcome this issue, a novel optical sensor application is presented, using off-the-shelf optode technology (MOPP). The application is validated using microprofiling, during a CCS leakage experiment, where the impact and recovery from a high CO2 plume was investigated in two types of natural marine sediment. MOPP offered user-friendliness, speed of data acquisition, robustness to sediment type, and large sediment depth range. This ensemble of characteristics overcomes many of the challenges found with other pH measuring methods, in OA and CCS research. The impact varied greatly between sediment types, depending on baseline pH variability and sediment permeability. Sedimentary pH profile recovery was quick, with profiles close to control conditions 24 h after the cessation of the leak. However, variability of pH within the finer sediment was still apparent 4 days into the recovery phase. Habitat characteristics need therefore to be considered, to truly disentangle high CO2 perturbation impacts on benthic systems. Impacts on natural communities depend not only on the pH gradient caused by perturbation, but also on other processes that outlive the perturbation, adding complexity to recovery.

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Réalisé en cotutelle avec le laboratoire M2S de Rennes 2