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Plutonium(VI) spectrophotometry is a precise analytical method for determining the concentration of plutonium solutions. It is simple and cost-effective to implement in nuclear environments such as glove boxes and hot-cells. Uncertainties were assessed at 0.64% (k = 1) for solutions of 0.150 mg g−1 initially prepared in a glove box. The critical limit of the method was estimated at 0.002 mg g−1 at 99% confidence. The good performances of the technique in the present work are due to a rigorous spectra processing as well as preparation steps conducted by weight control.

There is a critical limit of thrust force during drilling operation in a composite laminate below which no delamination takes place, which is known as the “critical thrust force”. In this paper, various critical thrust force models have been discussed in detail for circular- and elliptical-shaped delaminations around the drilled hole. Critical thrust force models for circular-shaped delamination for isotropic composite laminates and anisotropic composite laminates for different loadings like point load, uniformly distributed load, triangular load, and their combinations using different drill geometries have been discussed. With elliptical-shaped delamination, critical thrust force models for anisotropic composite laminates are discussed for: point load, uniformly distributed load, combined point plus distributed load, and point load for antisymmetric composite laminates. At several locations, graphs have been created to illustrate the dependence of various parameters on the critical thrust force. These graphs will be of use for practising engineers while selecting tool or/and machining parameters during drilling of polymer matrix composites. A tool designer can get good insight from these graphs while designing an optimal drilling tool. The paper highlights the importance of load distribution across the drill causing deflection leading to damage due to delamination in composite laminates. Special drill geometries help in better distribution of thrust forces towards periphery and improve the critical thrust force for the prevention of damage due to delamination during drilling in composite laminates.

The local buckling behavior of pipes under combined external pressure and axial tension is investigated by experiments and FE models in the present study. The tension-pressure interaction collapse envelops are generated for two different loading paths involving pressure followed by tension and tension followed by pressure. Ten experiments are conducted to study the effect of different loading paths on the collapse pressure of pipes with the same geometric and material parameter. Furthermore, an extensive parametric study of the FE models is performed whose results are in good agreement with the experiments. The results of the experiments and FE models indicate that critical limit load of the P→T loading path is more severe than that of the T→P loading path. The reason is explained by analyzing the stress distribution and ovalization of the local buckling cross section. Based on the large amount of FE analyses, a new interaction formula is proposed to estimate the limit loads of pipes for the P→T loading path. And the formula, verified by experiments, is more accurate comparing with the method proposed in offshore standard DNV-OS-F101.

High-pressure conditions in diesel engines can often surpass the thermodynamic critical limit of the working fluid. Consequently, the injection of fuel at these conditions can lead to complex behaviors that remain only incompletely understood. This study is concerned with investigating the application of a diffuse-interface method in conjunction with a finite-rate chemistry model in large-eddy simulations of diesel spray injection and ignition in a supercritical ambient environment. The presented numerical approach offers the capability of simulating these complex conditions without the need for parameter tuning that is commonly employed in spray-breakup models. Numerical simulations of inert and reacting n-dodecane sprays — under the Engine Combustion Network Spray A and Spray D configurations — are studied, and results are compared with experimental data for liquid/vapor penetration lengths and ignition timing. In addition, parametric studies are performed to identify flow sensitivities arising from the variation in nozzle diameters between both injectors, along with the impact of low-temperature oxidation on ignition in Spray D simulations. Spray A simulations are found to be insensitive to turbulence, and predictions for penetration length and ignition behavior are in good agreement with experiments. In contrast, Spray D predictions for penetration length and ignition delay demonstrated significant sensitivities to in-nozzle turbulence, introducing uncertainty to the predicted results and stipulating the need for quantitative measurements for model evaluation.

To better determine the lower limit of titanium content for the formation of acicular ferrite, C–Mn steel welds varying the titanium concentration at a minimal level from nearly zero to about 30 ppm have been investigated. Optical and SEM observations of as-deposited weld microstructures showed that when the titanium content increased from 1 to 9 ppm or higher, a dramatic change in weld microstructure from one dominant with ferrite with second phase to one with acicular ferrite takes place, being attributed to a concurrent increase in nucleation potency of inclusions for acicular ferrite plates. These results suggest that the critical limit of titanium required is about 9 ppm or even lower for the present weld system. In TEM, the inclusions of titanium-containing welds were found to be partly covered with a titanium-rich phase, indicating that this phase plays an important role in promoting the nucleation ability of inclusions and thus in developing a weld microstructure composed of a high proportion of acicular ferrite.

Thermal noise associated with the mechanical loss of current highly reflective mirror coatings is a critical limit to the sensitivity of gravitational-wave detectors. Several alternative coating materials show potential for reducing thermal noise, but cannot be used due to their high optical absorption. Multimaterial coatings have been proposed to enable the use of such materials to reduce thermal noise while minimizing their impact on the total absorption of the mirror coating. Here we present experimental verification of the multimaterial concept, by integrating aSi into a highly reflective SiO_{2} and Ta_{2}O_{5} multilayer coating. We show a significant thermal noise improvement and demonstrate consistent optical and mechanical performance. The multimaterial coating survives the heat treatment required to minimize the absorption of the aSi layers, with no adverse effects from the different thermomechanical properties of the three materials.

This paper investigates the effects of the under bump metallization (UBM) on Electromigration (EM) reliability of SAC solder joints and presents evidence suggestive of hidden mechanisms controlling the EM failure. This conclusion is based on the observation that the EM resistance does not show a monotonic increase with UBM thickness, but rather decreases above a certain critical limit. Since a thicker UBM would provide a greater supply of Cu, our observation contradicts the conventional view on the role of UBM on prolonging EM failure. We initially ascribed it to the increased of EM-prone microstructures or weak- links at the SAC/UBM interface active in thicker UBM layers. This is considered to be due to a more even distribution of EM flux across the joint by reducing current crowding at the corners of the joint. However, switching the test configuration, reducing current crowding, yielded results that disagreed with our proposition. It is found that the impact of the current configuration, and thereby the level of current crowding, on EM resistance does not vary much with the UBM thickness. This defies initial prediction that there would be a smaller impact in samples with thicker UBMs when the current configuration is switched. These results suggest that the EM failure mechanism is affected by UBM in a more complicated manner. Considering hidden factors such as the change in thermal stress with UBM thickness that act against the growth of EM void is necessary in order to better understand the mechanism.

One of the common causes of cross-linked polyethylene (XLPE) insulation ageing and finally cable failure is the presence of a cavity within cable insulation. Gas filled cavities can be initiated in XLPE cables during its manufacturing, installing and operating conditions. Once the size of the cavity reaches the critical limit, noticeable partial discharge (PD) activity develops. Therefore, the size of the cavity is one of the important factors that considered when investigating the PD activity in power cable. This work studies the effect of cavity size on PD behaviour within insulation layer of an 18/30 kV XLPE cable specimen; the changing in an artificial spherical cavity depths and diameters is investigated in the laboratory. In addition, 2D model geometry of a cable insulation having an artificial cavity is also developed using COMSOL software and MATLAB program to simulate the PD measurements from the laboratory experiments to imitate the conditions found during measurements, hence interpreting the obtained experimental results and determining the significant parameters influencing PD activity; hence, more a fuller understanding of PD phenomena within a cavity. The results show good coincidence between experimental and simulated data, in terms of PD magnitude and PD inception voltage.

Yttria stabilized zirconia (YSZ) is inevitable in many industrial applications. Yttrium additions in ZrO2 system induces either tetragonal (t-ZrO2) or cubic (c-ZrO2) phase stabilization that predominantly depends on the yttrium content. Here, the structural changes in ZrO2 system upon a wide range of yttrium additions are investigated. Powder synthesis is carried out through citrate-nitrate assisted sol-gel technique and analytical techniques involving XRD, Raman spectra and structural analysis through Rietveld refinement were utilized to investigate the structural changes in ZrO2 upon progressive yttrium additions. The critical limit of yttrium content to retain unique t-ZrO2, mixtures of t-ZrO2 and c-ZrO2 and discrete c-ZrO2 is determined.

This paper investigates the early fracture of the ductile metals under cyclic loading due to the occurrence of temperature-induced buckling (TIB). Extensive experiments with cylindrical dog-bone specimens made of SS316 and SS321 subjected to cyclic loading reveal that TIB occurs at a stress level below the buckling strength and before what inelastic cyclic buckling criterion predicts. It is shown that buckling occurs if the operating stress is at or above a critical limit σTIB and when the specimen's temperature reaches a critical limit, called TTIB. The analysis of the temperature evolution of these materials shows three distinct regions of Pre-TIB, TIB, and rapid failure thereafter. The measured TTIB for SS316 and SS321 are found to be 100 ○C and 130 ○C, respectively. The corresponding σTIB for SS316 and SS321 are 340 MPa and 365 MPa, respectively.

Steel plate girders with long or unstiffened web panels are often tapered to produce optimized members in buildings and bridges. Web shear strength is a critical limit state for these members because they usually have slender webs. Historically, shear has been apportioned to the web using two methods. The most common method is to assign the entire shear to the web. Alternatively, the Modified Shear Method considers the vertical component of each flange force resulting in web shear force not equal to the total shear. The first objective of this research was to experimentally determine the accuracy of these methods. It was found that the Modified Shear Method accurately predicted the shear resisted by the web at all 18 instrumented cross-sections in ten tested specimens. Several methods for predicting shear strength of unstiffened and long prismatic web panels are available in the literature. The second major objective of this research was to determine if one or more of these methods accurately predicts tapered member shear strength. Measured ultimate shear strengths were compared to predictions. Methods based on Basler's method provided inaccurate predictions. Methods based on Hoglund's method and the method by Lee and colleagues provided accurate predictions.

Nichtbeluftete Flachdachkonstruktionen in Holzbauweise erfordern aufgrund ihrer Kompaktheit tiefere Kenntnisse hinsichtlich deren bauphysikalischer Vorgange im Dach. Dabei weist vor allem die Dachschalung aus Holz unterhalb der dampfdiffusionsdichten Schicht ein feuchtetechnisch erhohtes Gefahrenpotential auf. Untersuchungen haben gezeigt, dass eine Uberschreitung von 20 % Holzfeuchte uber eine langere Zeitdauer erhebliche Folgen wie Befall durch Schimmelpilze oder holzzerstorende Pilze bedeuten kann. Auch die Verklebung kann bei so hohen Holzfeuchten deutlich beeintrachtigt werden. Aus diesem Grund wurde im Rahmen eines Forschungsprojektes beim Neubau eines Zweifamilienhauses Messtechnik im Hohlkastensystem installiert und die Konstruktion uber mehrere Jahre uberwacht. In die Dachkonstruktion wurden vergleichend Mineralwolle- und eine Holzfaserdammung eingebaut. Zur Beurteilung des Feuchtegehaltes der Dachschalung wurde dabei auf zwei experimentelle und ein numerisches Verfahren zuruckgegriffen. Das erste experimentelle Verfahren basiert auf der Berechnung der Holzfeuchte aus den gemessenen relativen Luftfeuchten im Dach. Hierfur wurde speziell die Sorptionsisotherme der verwendeten Dreischichtplatten ermittelt. Parallel dazu wurde die Holzfeuchte mittels Widerstandsmessung in den Bereichen mit Holzfaser- bzw. Mineralwolledammung bestimmt. Zum Vergleich dieser experimentellen Verfahren wurde numerisch eine instationare hygrothermische Bauteilberechnung mittels WUFI® simuliert. Alle drei Verfahren ergeben plausible Ergebnisse. Aufgrund der maximalen Abweichungen von 2 % untereinander kann davon ausgegangen werden, dass sich der Verlauf der Ausgleichsfeuchte der Dreischichtplatte in einem Bereich zwischen ca. 11 bis 19 % Holzfeuchte bewegt. Somit liegt sie unter der kritischen Grenze von 20 % und stellt theoretisch keine feuchtetechnische Gefahr dar. Nichtdestotrotz muss aber die Feuchtebestandigkeit der Verklebung dabei unbedingt ebenfalls beachtet werden. Experimental and numerical investigation on the hygrothermal behaviour of flat roof elements made in hollow boxed construction. Due to their compactness non-ventilated flat roof constructions in wood require deeper knowledge about the construction-physical processes. The wooden roof sheathing below the vapour diffusion tight layer, in particular, runs an increased risk of hygric properties. Studies have shown that an excess of 20 % moisture content during a longer period of time implicates significant consequences, such as moulds, etc. The bonding can be significantly affected at such high moisture contents. For this reason, as part of a research project a measurement technology was installed during the new construction of a two family house and monitored over several years. For comparative analysis areas with mineral fibrous and soft fibrous insulating material were established. Two experimental and one numerical methods were applied in order to assess the moisture content of the installed three-layer panel. The first experimental method is based on the calculation of the moisture content from the measured relative humidity in the roof. For this, the sorption isotherm of three-layer panel used was determined. At the same time, the moisture content was recorded by resistance measurement in the areas with the mineral fibrous and soft fibrous insulating material. A transient hygrothermal calculation using the simulation program WUFI® was carried out for comparison of these experimental methods. All three methods produce plausible results. Because of the maximum deviation of 2 % of one from another it can be assumed that the fluctuating behaviour of the equilibrium moisture content of the three-layer panel most likely moves in a range between about 11 to 19 % moisture. Thus it is situated below the critical limit of 20 % and does in theory not constitute a risk of hygric properties. Nevertheless the range of 20 % is quite high, for which reason the moisture resistance of the bond thereby should be noted.

a b s t r a c t This study investigated the effects of packaging on physicochemical properties, bioactive components (anthocyanins, ascorbic acid and b-carotene) and shelf life of pomegranate arils (cvs. Arakta, Bahgwa and Ruby) obtained from fruit stored for a long-term (between 10 and 14 weeks). Headspace-volume-to-mass ratio of packaged arils had a significant impact on gas composition inside the packages, O2 concentrations was not below the critical limit (2%). Arils weight loss did not exceed 0.2%, while juice leakage ranged from 0.17 to 4.17 mL 100 g � 1 across all treatments. Physicochemical parameters were not significantly affected by packaging. However, there were significant differences in bioactive component amongst the cultivars, with cv. Bahgwa having the highest level of anthocyanin (112.50 mg L � 1 ) and b-carotene (6.20 mg L � 1 ). Based on visual quality and development of

Crystal structure and basic magnetic properties of the compounds RE(Mn,In)2 (RE = Ho, Tm, Er) were investigated. X-ray powder diffraction revealed the MgZn2-type of structure, space group P63/mmc, a = 5.691(1), c = 9.265(2) A for HoMn1.25In0.75, and a = 5.607(1), c = 9.176(2) A, for TmMn1.26In0.74; MgCu2-type, space group Fd 3 ¯ m; a = 7.556(1) A for ErMn1.85In0.15. The positions of the Mg atoms in the Laves phase structures are occupied by rare-earth atoms, and the positions of the small atoms (Cu or Zn) are occupied by a statistical mixture of Mn and In atoms. The unit cell expands by the In substitution, and crossing the critical limit for the Mn–Mn spacing can allow the formation of Mn moments. This can contribute to the magnetic randomness and presumably glassy behaviour.

The regular patterns of initiation and show of acoustic emission memory effect in a composite are experimentally obtained from tests on cloth laminate. The authors illustrate the capacity of cloth laminate as an absolute sensitive stress-to-acoustic emission converter. The designed and tested in-hole sensor enclosing this converter indicates when incremental stress surpasses a pre-assigned critical limit.

Stress intensity factor (K) is the measure of severity of stress at the crack tip. When K exceeds the critical limit (i.e., the material fracture toughness), the crack grows. K is valid in brittle materials (LEFM) and to some extent in ductile materials also provided there is small scale yielding (SSY) at the crack tip. The paper reviews the numerical methodology to obtain KI of ductile, Mode I cracked, CT and SENB test specimens in LEFM and SSY regimes with the help of J integral method. The numerical values are successfully compared with the theoretical values.

Compressive, indirect tensile, and flexural strengths characteristics of natural rubber latex modified concrete (NRLMC) were studied and reported — Part I. In addition, a comparative investigation between normal concrete (NC) and NRLMC, conducted on fire endurance was also presented — Part II. Normal and modified elements containing latex–water ratios within 0–10% were prepared and cured in accordance with the Japan Industrial Standard. Fire endurance capacity was assessed at five temperature levels; ambient temperature (27 °C), 150, 300, 500, and 800 °C. However, elevated heating (800–1300 °C) was further applied for the purpose of monitoring behavior at the verge of disintegration. Specimens were allowed to cool in the oven prior to compressive strength tests until room temperature is attained. Test results indicate that significant mechanical capabilities could be achieved by the inclusion of an appropriate quantity of latex concentrate and proper selection of befitting curing regime. Interestingly, the superiority of NRLMC over NC is maintained even under fire, up to the critical limit of latex-film capability performance.

This research aims to quantify fracture limits of hollow silicon microneedles due to axial and shear forces, and validate their use on human skin. Needle failure due to axial and shear loads may be due to heterogeneous peak stresses within the bulk material. Analytical determination of physical usage limits of microneedles can be misleading, as beam fracture models do not translate well to the micro-scale. In this research, various sizes of hollow silicon microneedles were fabricated. Their point of failure due to fracture was tested via application of axial and shear forces. Axial fracture of 36 gauge silicon microneedles took place at about 740 gram-force. It was determined that the axial force experienced by microneedles during insertion into human cadaver skin, is much lower than this critical limit, and thus needle failure due to breakage can thus be generally attributed to shear forces. Fracture limits of microneedles due to shear forces were quantified; ranging from about 36 gram-force for 36 gauge needles to about 275 gram-force for 33 gauge needles.

Producing energy to supply the demands of our societies is reaching a critical limit. To tackle this issue, there is a slow renaissance of fission reactors and the push to realise fusion reactors. The safe, reliable and optimal performance of fusion and fission plants is dependent on the choice of suitable materials used as components and fuels. As these materials are degraded by their exposure to high temperatures, irradiation and a corrosive environment, it is necessary to address the issue of long term degradation of materials under service exposure in advanced plants. A higher confidence in life-time assessments of these materials requires an understanding of the related physical phenomena on a range of scales from the atomic level of single defect energetics all the way up to macroscopic effects.

This paper experimentally investigates the effect of time and pressure on the condition of polishing pads and the material removal rate (MRR) of single crystal silicon. It was found that as the pad deteriorates with time, MRR decreases. Surfaces with a required quality can only be achieved before the texture deterioration reaches a critical limit. At a higher pressure, 25 kPa, deterioration is slower, and the effective life of pads and MRR is enhanced.

水工用アスファルト混合物の低温ひび割れ抵抗性を評価する研究の一環として, リング状の拘束体の外周にアスファルト混合物を打設, 転圧した供試体を低温環境下に曝してひび割れを発生させ, アスファルト混合物の材料・配合条件, 拘束条件, 温度履歴条件などがひび割れ発生温度に及ぼす影響を把握するとともに, ひび割れ発生時にアスファルト混合物に作用しているひずみや応力, 粘弾性体から弾性体に移行する転移点温度について検討を行った. また, アコースティックエミッションの測定によりアスファルト混合物に微細ひび割れの発生が開始される温度を把握し, 転移点温度や貫通ひび割れ発生温度との関係, 微細ひび割れの発生メカニズムなどを示した.

コンクリートのひび割れ発生時期を予測する研究の一環として, 一軸拘束試験体を用いてコンクリートの収縮によりひび割れを発生させ, 各種の要因がひび割れ発生時期に及ぼす影響, ひび割れ発生点近傍のひずみの挙動, 引張伸び能力や収縮応力強度比のひび割れ発生限界点としての適用性などについて検討し, さらに, 逐次解析を行い実験値と解析値の比較を行った. その結果, コンクリートの収縮ひずみが部材内で均一でないことがひび割れ発生時期をばらつかせる原因であること, ひび割れ発生に影響を与えている範囲から算定した引張伸び能力や, 強度発現条件を考慮した収縮応力強度比は, ひび割れ発生時期を予測する限界点として実用上適用できることなどを示した.

In order to guarantee the oxidation resistance of Cr-steels the Cr content in the alloy must be above a critical limit. Recently developed 9Cr steels are close to that limit and as ongoing oxidatio...

Publisher Summary This chapter discusses the prediction of loss of corrosion resistance in austenitic stainless steels. Austenitic stainless steels contain a combination of Cr and Ni, which makes them fully austenitic under most practical conditions. The Cr content is usually about 18 wt% or higher, which is well above the critical limit for corrosion resistance, about 12 wt% Cr. An accurate calculation of the formation of the depleted zone would require a detailed consideration of the diffusion-controlled growth of the C-rich carbide. However, a rough estimate can be made from the thermodynamic information on the Fe–Cr–Ni–C system. The chapter presents the calculations that were carried out using the Thermo-Calc databank. It has a special feature for automatic calculation of diagrams involving two different but related equilibria in each step. For the calculations presented in the chapter, information on austenite and M23C6 were used.

We are interested in strain accumulation process in polymeric materials when exposed to periodic (cyclic) loading. Within each loading cycle material undergoes a combination of the creep and relaxation process. At certain conditions the retardation process between two loading cycles cannot be fully completed. Consequently strain starts to accumulate, which leads to hardening of the material and ultimately to the failure of polymeric product. Taking into consideration the importance of the mechanical spectrum of polymeric material for predicting durability of dynamically loaded polymeric products, [1], we present the analysis of the effect of the “shape” of material time‐dependent properties, expressed with the mechanical spectrum, on the process of strain accumulation under periodically applied loading. We observe, that spectrum shape defines the intensity and the magnitude of strain accumulation process. For certain type of material the accumulated strain will almost certainly lead to the failure of the product, while material with different time‐dependent characteristics will not experience the critical limit of accumulated strain that would cause failure.

Tailoring electronic and optical properties of self-assembled InAs quantum dots (QDs) is a critical limit for the design of several QD-based optoelectronic devices operating in the telecom frequency range. We describe how a fine control of the strain-induced surface kinetics during the growth of vertically-stacked multiple layers of QDs allow to engineer their self organization process. Most noticeably, the present study shows that the underlying strain field induced along a QD stack can be modulated and controlled by time-dependent intermixing and segregation effects occurring after capping with GaAs spacer. This leads to a drastic increase of TM/TE polarization ratio of emitted light, not accessible from the conventional growth parameters. Our detailed experimental measurements supported by comprehensive multi-million atom simulations of strain, electronic, and optical properties, provide in-depth analysis of the grown QD samples leading us to depict a clear picture on atomic scale phenomena affecting the proposed growth dynamics and consequent QD polarization response., Accepted for publication in IOP Nanotechnology

It is recognised that the development of new alloys requires the commitment of increasingly large amounts of money and time which few corporations can these days afford. Techniques for short-cutting the development path are needed, e.g. predictive models. Two such methods are presented here for pre-determining alloy stability and strength. The pursuit of this and similar approaches should help to minimise the expense, and time, incurred in manufacturing and testing many unsuccessful alloy formulations. New alloys are still needed with property combinations which have yet to be realised. critical electron vacancy or “N,” value is determined for an alloy, below which it is judged stable over a set time and temperature. The problem with this system however is that a unique critical limit has to be established for each alloy that is assessed. This calculation is continually being refined with regard to the compositions of the various phases. More recently a modified approach involving the “d-electrons concept” (3) for SC alloy design has been extended to include also a measure of the bond strength of the alloying elements (4). In this way, the relative stability of an alloy could be displayed on a map, but the boundaries remain undefined.

A form of the sliding filament model is presented to simulate the experimentally observed phenomena when a contracting muscle is subjected to mechanical stretches. It is assumed that the cross bridges can be extended to provide extra tension and that they can be broken if a critical limit of extension is exceeded. Passive components, including non-linear parallel elasticity are incorporated in the model. Such effects as short-range stiffness, the slip effect and excess tension after mechanical stretch can be simulated. The simulations are compared with our own experimental tests on frog sartorious muscle and with previously reported results from other muscle preparations.

Fracture of an elastomer starts from small flaws where the local stress exceeds a critical limit for tearing. A criterion for the onset of tearing can be conveniently described in terms of a characteristic energy or a tearing energy which defines the fracture property and is independent of the form of the test piece.

Corrosion of reinforcing steel is now recognised as the most critical limit state affecting the durability of concrete structures. Of the various techniques used for corrosion protection, epoxy coating, together with effective water proofing, offers an efficient and economic means of protecting the steel. This paper discusses the engineering properties of epoxy coated reinforcement, and shows that it is possible to produce a coating that is strong, tough and resistant to salt spray and alkaline medium. The bond strength of such bars in concrete is dependent on the shape of the lug, and bars with lugs perpendicular to the axis gave nearly the same bond strength as uncoated bars. When exposed to natural and accelerated marine environment, epoxy coated bars are shown to have excellent corrosion resistant properties. Even when the coating is damaged, the corrosion damage suffered by these bars is far less than those of coated and galvanized bars.