Co-solvent concentration impact on the cloud point behavior of 2- and 3-ingredient systems of the poly(tridecyl methacrylate) in supercritical CO2

Cloud point data of the 2- and 3-ingredient poly(tridecyl methacrylate) [P(TDMA)] mixture in supercritical CO2 and dimethyl ether (DME) have been obtained experimentally with the variable volume-view cell at a high pressure.

Active system for reduction of noise parameters of car muffler with the use of pressure sensors based on silicon microcrystals

Purpose: The article contains the results of research and development of a system for active noise damping of an automobile engine. The proposed system of active noise suppression can significantly reduce the sound pressure level in the frequency band up to 500 Hz. The robotic principle of the developed system is based on the addition of an additional buffer tank with a variable volume in the silencer system. The use of high-temperature sensors with strain gauges based on silicon microcrystals to obtain information on the parameters of sound vibrations arising during the exhaust gas outflow made it possible to create a control system for changing the volume of the buffer tank. The results of testing the proposed system of active noise suppression of an internal combustion engine are presented. Design/methodology/approach: The active noise suppression system based on the Helmholtz resonator used tools to control general noise levels, experimental tests, complex mathematical modelling of acoustic processes in Solidworks, taking into account the conditions of propagation and attenuation of sound energy by intermediate closed volumes. Findings: The use of an additional resonator chamber with variable volume in the exhaust muffler of the internal combustion engine allowed to reduce the resonant phenomena in the zone of low-frequency pulsations of exhaust gas pressure from 57 Hz to 43 Hz at frequency drift in the range of 310… 350 Hz, which significantly improved its noise characteristics. Research limitations/implications: For further research, to improve the characteristics of the active noise suppression system, it is advisable to consider the use of several inadditional cameras of the Helmholtz resonator and to clarify the algorithm of the controller in transient modes of engine operation. Practical implications: The developed design of active noise reduction is simpler in comparison with analogs and allows reducing the noise of exhaust gases in a low-frequency range. Originality/value: To reduce the noise, a variable-volume Helmholtz resonator was used, the efficiency of which is provided by high-temperature sensors of the original design.

High Temperature and High Hydrostatic Pressure Cultivation, Transfer, and Filtration Systems for Investigating Deep Marine Microorganisms

High temperatures (HT) and high hydrostatic pressures (HHP) are characteristic of deep-sea hydrothermal vents and other deep crustal settings. These environments host vast and diverse microbial populations, yet only a small fraction of those populations have been successfully cultured. This is due, in part, to the difficulty of sampling while maintaining these in situ conditions and also replicating those high-temperature and high-pressure conditions in the laboratory. In an effort to facilitate more HT-HHP cultivation, we present two HT-HHP batch culture incubation systems for cultivating deep-sea vent and subsurface (hyper)thermophilic microorganisms. One HT-HHP system can be used for batch cultivation up to 110 MPa and 121°C, and requires sample decompression during subsampling. The second HT-HHP system can be used to culture microorganisms up to 100 MPa and 160°C with variable-volume, pressure-retaining vessels that negate whole-sample decompression during subsampling. Here, we describe how to build cost effective heating systems for these two types of high-pressure vessels, as well as the protocols for HT-HHP microbial batch cultivation in both systems. Additionally, we demonstrate HHP transfer between the variable-volume vessels, which has utility in sampling and enrichment without decompression, laboratory isolation experiments, as well as HHP filtration.

Markov Chain Monte Carlo Analysis of the Variable-Volume Exothermic Model for a Continuously Stirred Tank Reactor

In this paper, a variable-volume Continuously Stirred Tank Reactor (CSTR) deterministic exothermic model has been formulated based on the Reynold Transport Theorem. The numerical analysis of the formulated model and the identifiability of its physical parameters are done by using the least squares and the Delayed-Rejection Adaptive Metropolis (DRAM) method. The least square estimates provide the prior information for the DRAM method. The overall numerical results show that the model gives an insight in describing the dynamics of CSTR processes, and 14 parameters of the CSTR are well identified through DRAM convergence diagnostic tests, such as trace, scatter, autocorrelation, histograms, and marginal density plots. Global sensitivity analysis was further performed, by using the partial rank correlation coefficients obtained from the Latin hypercube sampling method, in order to study and quantify the impact of estimated parameters, uncertainties on the model outputs. The results showed that 7 among the 14 estimated model parameters are very sensitive to the model outcomes and so those parameters need to be handled and treated carefully.

Analisis Faktor Pencetus Sisa Hasil Usaha pada Koperasi Sisa Hasil Usaha Se-Kabupaten Jepara

The purpose of this study is to analyze the factors that trigger SHU in multi-business cooperatives in Jepara. The object of this research is the multi-business cooperative in Jepara district. The method of data collection in this study uses the method of literature study and documentation carried out at the Department of Cooperatives, small and medium enterprises, Manpower and Transmigration, Jepara. Data were analyzed using multiple linear regression analysis. The results of this study indicate that the factors that trigger SHU are the number of members, cooperative assets, business volume, own capital and external capital. The results of the t-test analysis show that the number of members, cooperative assets, own capital and outside capital have a positive effect on SHU, while the variable volume of business has a negative effect on the SHU.

THEORETICAL FOUNDATIONS FOR THE CREATION OF A «FRAME» GEOTECHNOLO-GY FOR UNDERGROUND DEVELOPMENT OF SUBSURFACE RESOURCES

A physical model of the process of underground ore mining is substantiated and it is shown that ensuring the geomechanical safety of subsurface development is associated with the technological capabilities of nature-like mining technologies for the reproduction of stable dy-namic structures in the lithospheric objects being worked out. A cognitive analysis of typical geotechnologies is carried out and it is shown that the modern geo-technological paradigm is based on the principles of combining in time the processes that generate a geomechanical dis-turbance in the lithosphere and the processes to overcome the consequences of this disturb-ance. The internally insoluble contradiction of this approach is revealed and it is shown that overcoming this contradiction opens up a very real prospect of creating a fundamentally new concept for the development of underground mining technologies based on the implementation of the global idea of nature-like technologies in the form of the concept of creating convergent mining technologies. With the use of the proposed and developed by prof. The Rodionov model of the lithosphere as a solid body with different-scale inhomogeneities performed a theoretical study of the features of the stress field development during the formation of inhomogeneities with variable volume and zero density and found that in this case, the conditions for the repro-duction of stable dynamic structures will be determined by processes on the external contour of inhomogeneities. This made it possible to substantiate the geophysical and geotechnological ideas of a new technological paradigm of subsurface exploration.

Silicone Rubber Used for Lower Limb Prostheses

The liner is one of the most important part of the lower limb protheses, whose role is to maintain the contact between the residual limb and the socket. Taking into account the residual limb has a variable volume, we have analysed the closed-cell prototype of the liner made of silicon rubber RTV-2. The mechanical properties of this material could provide the requirements imposed for the lower limb prostheses. Meantime it is innocuous for the human body, especially for skin contact and could be used for medical devices manufacturing.