Temporal variation of voids in waxy crude oil gel in the presence of temperature gradient

Abstract

The formation of voids is eminent below the pour point temperature of waxy crude oil. This paper discusses the temporal variation of voids in waxy crude oil gel in the presence of temperature gradient between the waxy crude oil and its ambient condition. Cooling of waxy crude oil to an end temperature of 10?°C was performed in a flow loop rig, after which it was scanned in a 3?T Magnetic Resonance Imaging (3?T-MRI) system. Five consecutive scans with equal intervals were taken and analyzed to observe the variation of voids over the waiting duration. It was observed that the percentage of total voids volume reduced from 7.16% to 6.09%, from 6.59% to 5.71% near a pipe wall, and from 0.57% to 0.38% around a pipe core at waiting duration of 50?minutes. A waiting duration of 10?minutes reduced the voids volume around the pipe wall from 6.59% to 6.33%, and this was the maximum when compared with observations at higher waiting durations. The rate of voids disappearance was also higher at shorter waiting durations, with a maximum of 0.032%/min rate of change of voids observed at 10?minutes. Conversely, a minimum of 0.002%/min rate of change of voids was observed at 40?minutes waiting duration, beyond which the difference was almost insignificant. The disappearance rates were small that the change in voids volume became minimal over longer waiting durations, showing insignificant voids variation with surrounding weather conditions.     

Circular economy in RFID technology: analysis of recycling methods of RFID tags

Circular Economy (CE) is one of the approaches which are intensively developed and tested in different areas of industry and services. The aim of this solution is to use many kinds of resources in a closed flow and to achieve as a small amount of waste as it is possible.

One of the potential areas of using CE is Radio Frequency Identification (RFID). In RFID systems tags are utilized in various forms. This paper addresses investigation of a recycling process of RFID tags. Different attachment methods of these tags were tested and then, a recycling procedure was prepared based on the obtained results in which adhesives are recommended to be used as an attaching material between a tag and an identified object. The mentioned procedure was evaluated with using paper-face RFID tags. It was confirmed applicability of the proposed solution. Moreover, the conducted research revealed that an adhesion force of the adhesive layers in the prepared RFID tags decreased in the most extent during the first recycling cycle. It was found that in order to preserve a high adhesion force of these layers it is suggested to place the tags on a clean surface.     

Optimal Production Control in Stochastic Manufacturing Systems with Degenerate Demand

The paper studies the production inventory problem of minimizing the expected discounted present value of production cost control in manufacturing systems with degenerate stochastic demand. We have developed the optimal inventory production control problem by deriving the dynamics of the inventory-demand ratio that evolves according to a stochastic neoclassical differential equation through Ito’s Lemma. We have also established the Riccati based solution of the reduced (one-dimensional) HJB equation corresponding to production inventory control problem through the technique of dynamic programming principle. Finally, the optimal control is shown to exist from the optimality conditions in the HJB equation.     

丁香中总黄酮含量测定及提取工艺研究

以NaNO、Al (NO3)3、NaOH与黄酮类化合物作用后生成红色络合物,以芦丁为标准品,采用了分光光度法测定丁香中总黄酮的含量并研究了黄酮提取的工艺条件.考察乙醇浓度,提取温度,提取时间和提取次数4个因素对丁香中总黄酮提取工艺的影响,并通过正交试验确定了最佳的提取工艺.结果表明,丁香中总黄酮含量为6.25％.黄酮提取的最佳工艺条件为乙醇浓度为40％vol,提取时间为3h,提取次数4次,水浴温度65℃.利用此法简便可行.     

A liquid diffusion model for thin-layer drying of rough rice

In this study, the drying behavior of single-layer rough rice with a moisture content of between 22 and 24% on the dry basis was simulated by means of a liquid diffusion model, based on a prolate spheroid geometry. For this purpose, the solution of liquid diffusion equation was fitted to the experimental moisture ratios for drying air temperatures between 40 and 60 °C and velocity 1.5 m s⁻¹. In order to make a comparison, the predictions of liquid diffusion equations for a spherical and finite cylindrical geometry were also fitted to the experimental results. Modeling was performed by selecting the diffusion coefficients in diffusion equations in such a manner as to minimize the sum of the squared differences between the experimental results and the theoretical predictions. It was found that the liquid diffusion model, based on a prolate spheroid geometry, explains single-layer drying behavior of rough rice well. It was also found that the model, based on a prolate spheroid geometry, has better agreement with the experimental results than the other geometries.     

Comparison of results of soil-structure interaction analyses based on time and frequency domain approaches with emphasis on treatment of damping

Comparison of results of soil-structure interaction analyses of the reactor building of a nuclear power plant using different analytical approaches and solution procedures is presented. The emphasis of the comparison was on the treatment of damping in these different approaches and procedures. An axisymmetric model of the reactor building was employed. The analyses were performed for the aircraft impact loadings. Two different locations were used for these loadings.The following four different sets of analyses were performed.

1. (1) Time-domain analysis using frequency-independent soil springs in conjunction with modal damping cut-off.

2. (2) Frequency-domain analysis using frequency-independent soil springs in conjunction with a complex modulus approach.

3. (3) Frequency-domain analysis using frequency-dependent soil-impedance coefficients in conjunction with a complex modulus approach.

4. (4) Frequency-domain analysis using frequency-dependent soil-impedance coefficients in conjunction with Rayleigh damping.

The frequency-independent soil springs were computed using the standard approach based on rigid base supported on an elastic layered half-space. The frequency-dependent soil impedance coefficients were computed in the form of a soil substructure matrix which included the uncoupled as well as the coupled terms. The computations were based on the use of a “flexible” base mat supported on a layered half-space. Unit dynamic loads, for each frequency, were applied to the layered half-space corresponding to each degree of freedom and the displacements were xomputed corresponding to all degrees of freedom. The compliance matrix so computed was inverted to obtain the impedance matrix for each frequency. The computations were repeated for all frequencies of interest for the aircraft impact loading.Floor response spectra were developed and compared at various floor elevations of the reactor building using the above four different sets of analyses. Conclusions were developed as a result of these comparisons.     

Magneto-optic ellipsometry in exchange-coupled films

Analytical representations of Jones matrices for the magneto-optic (MO) reflection in (a) a magnetic film on a magnetic substrate separated by a nonmagnetic spacer and (b) two ultrathin magnetic films separated by a nonmagnetic spacer, sandwiched between a nonmagnetic cover and a nonmagnetic substrate with arbitrary and independent orientations of magnetization, are provided. Originally isotropic media subjected to a uniform magnetization are considered. The discussion of MO response is restricted to the terms linear in the off-diagonal permittivity tensor elements, and typical situationsare illustrated numerically. The results are useful for the analysis of the experiments in MO ellipsometry and MO magnetometry of exchange-coupled magnetic ultrathin-film structures.     

Physico-chemical and technological studies on sugar beet roots

The morphological and chemical characteristics of ten varieties of sugar beet roots were evaluated during the season of 1996-1997. The best morphological characteristics were found in Top, Ito and Pamela varieties. The highest expected technological yield of sugar was found in Pamela and Top. The chemical constituents of different varieties of sugar-beet roots showed significant differences. The suitability of sugar beet juice for preparing beet syrup as a new product was also evaluated and compared with sugar cane syrup. Purified beet-syrups concentrated under vacuum or under atmospheric pressure showed more stability during storage than sugar cane syrup. The effect of storage conditions (at cold storage and at room temperature) and packaging materials (glass and polyethylene high-density bottles) on properties of beet-syrup and sugar cane syrup were also studied.     

Influence of harvest date and geographical location on kernel symptoms, fungal infestation and embryo viability of malting barley

This study focused on the influence of harvest timing and geographical location on spring malting barley (potential malting variety) in terms of fungal infestation and seedling viability in symptomatic and asymptomatic kernels. The study was conducted over two consecutive crop years (2003-2004) at four locations in Slovakia. The following categories of the barley kernels were used for the assessment: kernels with black point symptoms (BPK), kernels with black cover on their surface (BCK), pink-colored kernels (PCK) and asymptomatic kernels (AK). The occurrence of various fungi was detected in all kernel categories ranging from 60 to 100%. The most frequent fungal contaminants were members of the genus Alternaria, recovered from BPK in the range of 52.6-69.85%, BCK (62.36-73.28%) and AK (55.35-69.58%). The prevalence of Alternaria spp. was recorded for each harvest time. Other dematiaceous fungi, Epicoccum nigrum and Cochliobolus sativus were found with medium frequency in the same three categories. However, C. sativus was recovered with a higher frequency in BPK (2.6-25.3%). In PCK, the most commonly recovered fungi were species of Fusarium with F. avenaceum (59.2-93.2%) as the most prevalent. The infestation of kernels by fungi from other genera showed only low frequency within all the kernel categories investigated. There was no significant influence of the year and location on the proportion of the symptomatic kernel categories. Kernel germination was inhibited to a greater degree in the wetter and colder year. The strongest inhibition of germination ranging from 2.35 to 22.45% was recorded in PCK in all locations and both years. Germination declined from PCK to BCK (43.2-90.32%), and BPK (45.6-91.61%), while it was highest in AK at all harvest times (63-93.6%). This study found that the black covering symptoms (BCK) caused greater damage to viability of the kernels than black point symptoms (BPK). The delayed harvest time resulted not only in increasing numbers of discolored kernels and undesirable symptomatic kernel fractions but also in lower germination of the kernels tested.