Function Of Compression Force Research Articles

Straight and Bent Bars Buckling Considered as the Axial Displacement of One Bar End

Abstract A new approach has been taken to the problem of straight and bent bar buckling, where bar buckling is considered as a function of axial displacement of one end. It was assumed that the length of a bar being buckled at any instant of buckling is the same as that of a straight bar, regardless of the size of axial displacement of one end of the bar. Based on energy equations, a formula was derived for the value of axial displacement of one bar end or buckling amplitude in the middle of bar length as a function of compressive force. The established relationships were confirmed by simulation tests using the finite element software Midas NFX and by experimental tests.

Development and characterization of curcumin-loaded solid self-emulsifying drug delivery system (SEDDS) by spray drying using Soluplus® as solid carrier

The objectives of the current work were (a) to investigate the suitability of soluplus®, a hydrophilic polymer, as a carrier for the entrapment of curcumin (CUR) SEDDS by the spray-drying process, and (b) to compare soluplus® with neusilin® US2, a hydrophobic high-capacity adsorbent for solid SEDDS. Both carriers produced free flowing powders with high CUR entrapment efficiency. When filled into capsules, approximately 95% of CUR was dissolved from the soluplus® powder within 120 min and only 41% from the neusilin® US2 base powder. When the powders were compressed into tablets, a slow CUR release was observed over 24 h, which varied as a function of compression force and the percentage of disintegrant used. In conclusion, current study demonstrated the feasibility of using soluplus® as a carrier for the preparation of solid SEDDS with more favorable release profiles when compared to the conventional hydrophobic adsorbents.

Physico-fracture Characteristics of Makhana (Euryale ferox) Seeds

ABSTRACTThe fracture characteristics of Makhana (Euryale ferox) seed kernels were determined at moisture contents varying from 10.28 to 15.2% (dry basis), as a function of compressive force, deformation, and energy absorbed. The force required for kernel rupture decreased as the temperature and time of roasting increased while moisture content of the seed decreased. The deformation of the seed at the point of rupture was found to be in the range of 1.69 to 2.95 mm. Energy absorbed per unit volume, sphericity and angle of repose increased linearly with increasing moisture content and were found to be in the range of 310 to 822 mJ, 0.97 to 0.98, and 46 to 50°, respectively.

Single Cell Performance of PEFC Using the Surface-Treated Stainless Steel Bipolar Plate

1 .Introduction Polymer electrolyte fuel cells (PEFCs) have been attracting much attention in recent years. Bipolar plate is one of the most important components in PEFCs and requires many criteria. For example, sufficient corrosion resistance especially in case of metals, good mechanical property, processibility, gas-impermeability and low cost. Stainless steels are regarded as the most promising material because it could greatly reduce the production cost. On use of stainless steels as bipolar plate material, one faces intrinsic problem of corrosion. Better corrosion resistance would be achieved by the formation of passive films enriched with chromium. However, passive films, which are dielectric by nature, could deteriorate the electric contact to carbon gas diffusion layer (GDL). Many surface treatments have been proposed so far to improve the contact resistance. The authors have proposed electrophoretic deposition (EPD) of nanosized TiN-SBR composite on a stainless steel substrate1). In this study, the method is applied to type 316L stainless steel bipolar plates to evaluate single cell performance. 2 .Experimental details Commercially available type 316L stainless steel plate was finished with a diamond paste (6 μm) and washed ultrasonically in hexane. TiN–SBR coating on the stainless steel surface was carried out by EPD process. The suspension was composed by 0.064 mass% of TiN (50 nm, Wako), 0.24mass% of emulsified SBR (NIHON Zeon) and 2-propanol. The prepared suspension was ultrasonically homogenized for 10 min. EPD treatments under a constant voltage (500 V) were controlled using a DC power supply. After the EPD, the stainless steel plates were vacuum dried. Interfacial contact resistance (ICR) of the treated stainless steel against carbon paper was evaluated as a function of compressive force. Polarization tests are carried out in a 0.05 M SO4 2-+ 2 ppm F- solution (pH: 3.3) at 353 K using a saturated calomel electrode (SCE) as a reference electrode. Bipolar plates after the design by JARI2) with serpentine flow field were machined with the type 316L stainless steel. Graphite bipolar plates were also used for comparison. A single cell was assembled from the bipolar plates and a commercially available MEA employing carbon paper GDL. The single cell was operated at 348K under an ambient pressure for 500 h. The applied current densities were 0 and 0.5 A cm−2. After the cell operation, the surfaces of the bipolar plates were analyzed by SEM and XPS. The contamination level of MEA was evaluated by XRF analysis. 3 .Experimental results and discussion After the EPD treatment, ICR between the stainless steel and carbon paper was improved from 63.2 mΩ cm2 to 10.7 mΩ cm2 (at 100 N cm-2), while the ICR between graphite and carbon paper was 4.5 mΩ cm2. The initial i-V characteristic for cells employing different bipolar plates (untreated 316L, treated 316L and graphite) indicated comparable voltage for treated 316L to graphite, while untreated 316L showed the lowest voltage due to iR drop. The difference expanded as the cell operation proceeded. The cell voltage under applied current density of 0.5 A cm−2 after 500 h operation were 0.648 V for graphite, 0.633 V for treated 316L and 0.616 V for untreated 316L. The change in open circuit voltage (OCV) was also evaluated for 500 h. The OCVs after the cells were left under open circuit condition for 500 h were 0.810 V for graphite, 0.807 V for treated 316L, 0.633 V for untreated 316L. The XRF analysis of MEA after the cell operations indicated highest concentration of iron for the cell with untreated 316L, while the contamination was successfully suppressed for the treated 316L. References 1) M. Kumagai et al., Electrochem. Acta, 54 574(2008). 2) Japan Automobile Research Institute, NEDO Report (12-17-013-2-0002-2), 2001, p. 21.

Rolling resistance of marine airbags at the longitudinal inclined slipway during ship launching

There are three principal methods of launching a new ship including gravitational launching, floating-out launching and mechanical launching. A launching with marine airbags is a new kind of gravitational launching; it allows launching the ships which DWT is below 60,000 tonnes. In this paper the authors consider the ship launching by using marine airbags. The main principle of airbag ship launching is based on changing the force of sliding friction into rolling friction. One of the important characteristics of such devices is resistance force which occurs during airbag rolling under the compressive load. This force can be named rolling friction, however the authors show that the mechanism of the resistance force during airbag rolling, is fundamentally different from the well-known mechanism of rolling friction which occurs during rolling of the solid deformable body. The authors show that the rolling friction coefficient of airbags and ground depends on the ground situation and airbag bearing forces. The authors determine the marine airbag shape and three components of the force of rolling friction depending on geometric parameters and values of pulling and compressive forces. The authors show that the main component of this force is related to appearance of bending moments in the airbag shell during its rolling. The authors have shown that coefficient of rolling friction as a function of compressive force has a minimum after which it slightly depends on compressive force. The method of calculating the motion of a ship in case of ship launching from the longitudinal inclined slipway by using marine airbags is discussed.

Volumetric breast density characteristics as determined from digital mammograms

In this paper we present the results of an automated and entirely reproducible algorithm that estimates the breast volume, dense tissue volume and the volumetric breast density from digital mammograms. The algorithm was applied to 55 087 digital images (CC view only) from 15 351 individual women, acquired between 2008 and 2011 at the Sunnybrook Health Sciences Centre in Toronto, Canada. The algorithm is based on a prior calibration of the digital image signal versus tissue thickness and composition, and the thickness of the compressed breast is estimated using an empirical model that corrects the thickness readout of the mammography system as a function of compression force. The mean volumetric density and breast volumes for our study group were 30% and 687 cm3, respectively. The left and right volumetric density and breast volume were strongly correlated, with a Pearson correlation of 0.92 and 0.91, respectively. The volumetric density decreased from 45% to 25% as age increased from 35 to 75 years, with an increase to 30% at 80 years. For a given woman, the volumetric density decreased at an average rate of -2 density percentage points per year while the breast volume increased by 2% per year.

Local and average gloss from flat-faced sodium chloride tablets

The purpose of this study was to detect local gloss and surface structure changes of sodium chloride tablets. The changes in surface structure were reflected by gloss variation, which was measured using a diffractive optical element-based glossmeter (DOG). By scanning a surface area, we constructed a 2-dimensional gloss map that characterized the tablet's surface structure. The gloss variation results were compared with scanning electron microscopy (SEM) images and average surface roughness values that were measured by conventional diamond stylus profilometry. The profilometry data showed a decrease in tablet surface roughness as a function of compression force. In general, a smoother surface contributes to higher average gloss values. The average gloss values for this material, in contrast, showed a decrease as a function of the compression force. The sequence of particle fragmentation and deformation together with crack formation in sodium chloride particles resulted in a loss of gloss for single sodium chloride particles at the tablet surfaces, which could be detected by the DOG. These results were supported by the SEM images. The results show that detailed information regarding tablets' surface structure changes can be obtained by detection of local gloss variation and average gloss.

Structural and Physical Properties of GDL and GDL/BPP Combinations and their Influence on PEMFC Performance

AbstractThe change in the structural and physical properties of the components assembled in a fuel cell stack, when being compressed, is important for performance evaluation. The physical properties of Gas Diffusion Layer (GDL) materials, such as thickness, through plane resistivity and gas permeability and pore size data are presented as a function of compressive force. The data obtained are correlated with fuel cell performance data. Beyond the materials and components specific properties the behaviour of combinations of BPP and GDL materials, which are manufactured by SGL Technologies GmbH, are evaluated and presented. Through plane resistance of a GDL‐BPP‐GDL sandwich is evaluated for varied compression forces and materials permutations.

Creep Characterization Of Ceramic BGA

Long term creep of a ceramic ball grid array (CBGA) solder ball under compressive loading was investigated. An experiment was conducted with two levels of loading and four of temperature. Analysis of the data assumed the composite ball structure could be simulated by an interconnection having the same shape, but of a single equivalent material. Curve fitting determined the stress exponent and activation energy of the equivalent material in the Norton creep model; the values were consistent with the range of values of the individual components available in the literature. Nonlinearity of the change in ball height with time was hypothesized to be due to geometric stiffening, a hypothesis which was confirmed by a simplified model. The model may be used to estimate creep behavior of other ball geometries having the same material set. The final result of this work - a closed form equation describing height decrease as a function of compressive force, temperature and time - can be used to simplify complex modeling of an entire package, and as an aid in designing accelerated thermal cycles which appropriately synchronize solder creep and fatigue.

Force-time curves of a rotary tablet press. Interpretation of the compressibility of a modified starch containing various amounts of moisture.

On a rotary tablet press, the force-time curves are segmented into three phases: the compression phase, the dwell phase during which both stress and strain are variable for plastically deforming materials and the decompression phase. The following seven parameters were investigated: the compression area (A1) and the compression slope (Slc) describing the initial phase, the area ratio (AR) and the peak offset time (t(off)) characterizing the dwell time, the decompression area (A4) and the decompression slope (Sld) describing the terminal phase and the total area under the force-time curve (Atot). AR, t(off), Slc and A1 (the last with limitations) are used for phase-specific allocation of the occurrence of plastic flow, which is found to be a function of compression force and moisture content. Tablet strength, tablet porosity and in-die bulk porosity provide additional information for comprehensive interpretation. The values of A4 for the four starch batches are not significantly different. Sld provides somewhat better information about the elastic compact recovery. In general, however, the short decompression phase seems to be inappropriate for characterization by force-time curve parameters, because it is difficult to separate machine recovery from that of the tablet. Porosity above the porosity limit of the material was found to be a prerequisite for plastic flow within the compact. When the porosity limit is reached, further densification remains elastic and leads to a reduced compact strength during expansion. The area ratio, as a robust in-process control parameter for plastically flowing formulations, is suggested as a means of preventing this effect.

Observations on the Dissolution Behavior of a Tablet Formulation: Effect of Compression Forces

Two test drugs, hydrochlorothiazide and phenylbutazone, were separately incorporated into a standard formulation to study their disintegration and dissolution properties as a function of compression force. The increase in dissolution with force was attributed to the manner in which tablets disintegrated while dissolving. At a fixed press setting, tablets from the same compression cycle showed variations in their dissolution which were in agreement with the observed effects of force on dissolution. A linear correlation between dissolution efficiency and the logarithm of force was found to exist over the compression range studied.

Preferred orientation of crystalline particles within tablets. III. Change in degree of preferred orientation of aspirin crystals during compression (author's transl)

The degree of preferred orientation of aspirin crystals in a tablet as a function of compression force was measured using the X-ray diffraction method. Preferred orientation took place during compression and the degree was affected by the size and morphology of the crystals. Thin, plate-like crystals had the strong tendency to orient preferentially at an early stage of compression, while pulverized crystals oriented gradually at over 100 kg/cm2 of the compression force. In addition, volume, specfic surface area, pore size distribution and breaking strength of the tablets were measured and the relationship among these factors was investigated.