Critical Technical Parameters Research Articles

Investigation of flocculation behavior of tailings during settling-concentration: influence of true density, particle size, and mud layer height

The rapid concentration of tailings is a crucial initial step in the cemented paste backfill (CPB) process, as it ensures the stability of the backfilling slurry concentration and the continuity of the backfilling process. The structure of flocs plays a pivotal role in tailings concentration, directly contributing to such critical technical parameters as settling speed and bottom flow concentration. However, most of the current studies focus on flocculant addition rather than the tailings slurry itself. Also, there is a lack of uniform characterization of the flocculant structure in the flocculation and settling system. This study establishes a semi-quantitative assessment system for evaluating the fine structure of tailings flocs based on indicators such as the exposure state of coarse particles, floc size, and floc compactness (porosity). The findings reveal that, during the settling process, the higher true density of tailings (3.156 g/cm3) and intermediate particles (40 wt% of 38 μm–74 μm particles) attenuates the clamping effect of turbulence on settling, leading to a faster settling rate to 0.65 cm/s and 0.29 cm/s respectively. Moreover, in the thickening process, tailings located at the bottom of the mud layer expedite the precipitation of interstitial water within the floc structure through the combined influence of gravity and rake frame shear. Consequently, a denser floc structure forms, as evidenced by a higher concentration of bottom flow at a macroscopic level. This conclusion provides a theoretical basis for faster preparation of highly concentrated tailings slurry in CPB.

Mechanistic formulation and validation of cutting seam by energy-focusing blast for pressure relief of deep roadway

Coal sources still comprise a significant proportion of the global energy supply, especially for developing countries. As mining depth increases, roadway instability, failure, and burst become increasing concerns over deep resource utilization and mining safety. Cutting seam by energy-focusing blast (CSEFB) technique is a novel approach to mitigate the problems. Driven by the demand for further understanding and application, this study discusses the mechanistic formulation of CSEFB through theoretical analysis, numerical simulation, and field experiments. Results show that CSEFB uses the broken-expansion rock and roof-cutting effect to relieve mining stresses. The CSEFB angle and length are two critical technical parameters. The angle is the prerequisite for validating pressure relief, and the length is the condition for determining the relief degree. The formulas are given for determining the range of angle and length. Within the range, the pressure-relief effect decreases modestly with increasing angle and increases significantly with increasing length. The standard length is proposed to use the support by bulking rock fully. An increase in the length can provide an additional effect by roof cutting itself, but this effect is limited as the length increases. This mechanism helps the formulation of CSEFB in the application. A bigger angle and the standard length are primary considerations. If requiring additional pressure-relief effect, a moderate increase in the length can add to pressure-relief effect by improving the stress field. Combined numerical simulation and field experiment with a typical high-stress deep mine, CSEFB exhibits good adaptability. Apart from relieving the high vertical stress, CSEFB avoids bad influences by the great horizontal stresses. The floor heave is exploited to facilitate the pressure-relief process. Research results have importance to the CSEFB application and promotion, thus contributing to the safety of deep mining.

Chemical covalent connection of carbon nanotubes for related structural manufacturing: A molecular dynamics study

Carbon nanotubes (CNTs) with junction plays an important role in nanomaterial and nano-devices, especially the junction constructed by covalent bonds. However, the connection process between single-walled carbon nanotubes (SWCNTs) could hardly be observed experimentally on an atomic scale and its connection strength is difficult to accurately measure. Hence, this work investigates the atomic reconstruction and evolution of the structure of SWCNTs at joint area and the connection strength of the joined SWCNTs by molecular dynamics (MD) simulation. Various connection effects between two types of typical SWCNTs, i.e. metallic SWCNTs and semiconducting SWCNTs, are investigated for the smooth covalent connection with high mechanical strength. The simulation results indicate that energy parameters (pulse-widths, pulse number, and temperature) and structure parameters (relative rotation angles, end type and chirality of SWCNTs) have great influence on the connection process. However, the size of energy zone and diameter for both armchair and zigzag SWCNTs make little difference to its connection process and connection strength under certain conditions. This study reveals that whether armchair or zigzag SWCNTs, there is an optimal set of energy and structure parameters to connect them into an ideal hexagonal junction with high mechanical strength. The critical technical parameters are obtained in this study for the optimal covalent connection of SWCNTs, which provides enlightening significance to manufacture the covalent SWCNTs junctions.

Investigation of corrosion and wear resistance of PEO coated D16T aluminium alloys in the marine tropical climate conditions

The effect of critical technical parameters such as the current density ratio between anode and cathode (ianode/icathode) and composition of the electrolyte solution on the morphology, structure, phase formation, hardness, abrasion, and corrosion resistance of D16T aluminum alloy with plasma-electrolytic oxidized (PEO) coatings was studied. The research results show that the properties and morphology of the obtained coatings are different when the technological regime is changed, and substances are added to the basic electrolyte solution. Aluminum oxide, silicon oxide, cobalt oxide, and manganese oxide are the critical components of the coatings, which are split into an outside porous technical layer and an interior denser working layer. The coating obtained from the base electrolyte with Co(OH)2 has the best properties, morphology, and the highest corrosion resistance.

A Semisolid Micromechanical Beam Steering System Based on Micrometa-Lens Arrays.

Optical beam steerers have been widely employed for information acquisitions. Numerous beam steering schemes have been developed, and each of them can satisfy practical requirements for certain scenarios. However, there is still a lack of a comprehensive approach that is able to balance all of the critical technical parameters for wide range of applications. Here, a semisolid micromechanical beam steering system based on micrometa-lens arrays (MMLAs) is demonstrated. It is operated by manipulating the probe beam over two sets of decentered MMLAs potentially driven by high-speed piezo-electric motors. Small f-numbers, well-corrected aberration, and easy lateral reproduction of micrometa-lenses optimize the overall technical parameters. As a proof-of-concept, we implement such a device exhibiting diffraction-limited resolution within a large field of view of 30° × 30°. A three-dimensional depth sensing is also performed to demonstrate its potential in light detection and ranging applications.

Neuronal Cell-type Engineering by Transcriptional Activation.

Gene activation with the CRISPR-Cas system has great implications in studying gene function, controlling cellular behavior, and modulating disease progression. In this review, we survey recent studies on targeted gene activation and multiplexed screening for inducing neuronal differentiation using CRISPR-Cas transcriptional activation (CRISPRa) and open reading frame (ORF) expression. Critical technical parameters of CRISPRa and ORF-based strategies for neuronal programming are presented and discussed. In addition, recent progress on in vivo applications of CRISPRa to the nervous system are highlighted. Overall, CRISPRa represents a valuable addition to the experimental toolbox for neuronal cell-type programming.

Permeability of Oil Shale Under In Situ Conditions: Fushun Oil Shale (China) Experimental Case Study

Oil shale is a critical strategic energy source with very large reserves, and it is acknowledged as an alternative energy source to crude oil. Oil shale in situ retorting is the only technologically feasible method to achieve large-scale industrial development. In situ permeability is one of the most critical technical parameters for successful implementation of oil shale in situ retorting. In this study, the permeability of Fushun oil shale at different temperatures was investigated using a triaxial permeability testing machine under in situ conditions. The results show that the permeability of the oil shale under three-dimensional stress can be divided clearly into three stages from 20 °C to 600 °C. First, the oil shale remains almost impermeable from 20 °C to 200 °C. Second, in the temperature range from 200 °C to 350 °C, the permeability of the oil shale first increased and then decreased to almost zero at 350 °C owing to the dual constraints of the surrounding stress and additional expansion stress under in situ conditions. Third, from 350 °C to 600 °C, the permeability of the oil shale increased sharply and reached a maximum of 100 × 10−5 μm2 at 600 °C. Thermal cracking and solid organic matter pyrolysis were the main factors controlling the change in oil shale permeability in the test temperature range. The results suggest that the threshold temperature for oil shale permeability change was 350 °C under in situ conditions. In addition, under in situ conditions, the oil shale permeability decreased with increasing pore pressure at different temperatures. This work has direct applications for oil shale in situ large-scale exploitation.

On the investigation of energy saving aspects of commercial lifts

This paper investigates energy efficiency issues in modern lifts, based on the VDI 4707 guidelines, in the context of “KLEEMANN-LESS” research project, funded by national resources and the EU. The above analysis is applied to various lift types manufactured by the Greek multinational company ΚLEEMAN HELLAS. The obtained results indicate the relationship between critical technical parameters, such as the elevator driving system type and the standby energy consumption, according to the aforementioned standard. Furthermore, in the current work, new techniques for energy savings are proposed, employing realistic scenarios, which significantly enhance energy efficiency. Experimental work shows that an energy saving of up to 40% can be achieved. The outputs of the current work are not limited to lift models manufactured by KLEEMAN HELLAS, but concern the majority of lift manufacturers as well.

Benchmarking of protein carbonylation analysis in Caenorhabditis elegans: specific considerations and general advice

Oxidative stress has been extensively studied due to its correlation with cellular disorders and aging. In proteins, one biomarker of oxidative stress is the presence of carbonyl groups, such as aldehyde and ketone, in specific amino acid side chains such as lysine, proline, arginine and threonine, so-called protein carbonylation (PC). PC study is now a growing field in general and medical science since PC accumulation is associated with various pathologies and disorders.At present, enzyme-linked immunosorbent assays (ELISA) seem to be the most robust method of quantifying the presence of carbonyl groups in proteins, despite having some recognised caveats. In parallel, gel-based approaches present cross-comparison difficulties, along with other technical problems. As generic PC analyses still suffer from poor homogeneity, leading to cross-data analysis difficulties and poor results overlap, the need for harmonisation in the field of carbonyl detection is now widely accepted. This study aims to highlight some of the technical challenges in proteomic gel-based multiplexing experiments when dealing with PC in difficult samples like those from Caenorhabditis elegans, from protein extraction to carbonyl detection.We demonstrate that some critical technical parameters, such as labelling time, probe concentration, and total and carbonylated protein recovery rates, should be re-addressed in a sample-specific way. We also defined a procedure to cost-effectively adapt CyDye™-hydrazide-based protocols to specific samples, especially when the experimental interest is focused on studying differences between stimulating conditions with a maximised signal-to-noise ratio. Moreover, we have improved an already-existing powerful solubilisation buffer, making it potentially useful for hard-to-solubilise protein pellets. Lastly, the depicted methodology exemplifies a simple way of normalising carbonyl-related signal to total protein in SDS-PAGE multiplexing experiments. Within that scope, we also proposed a simple way to quantify carbonyl groups by on-gel spotting diluted dye-containing labelling buffer. Proof of the robustness of the procedure was also highlighted by the high linear correlation between the level of carbonyls and the ultraviolet exposure duration of whole worms (R2=0.993).Altogether, these results will help to standardise existing protocols in the growing field of proteomic carbonylation studies.

New energy value chain through pyrolysis of hospital plastic waste

In this paper, the evolution in thermochemical behaviours of hospital plastic wastes and changes in chemical composition and characteristics of pyrolysis liquid products have been investigated by using different fixed bed reactor scales. The main objective is to identify the critical technical parameters enabling thermochemical process adaptation in function of raw materials chemical structure, with the aim of maximising the yield of condensable fraction and optimising its energetic properties related to internal combustion engines.It is a step-by-step procedure using three reactor capacity levels, which allows various aspects approach of thermochemical process development from the evaluation of global reaction kinetic parameters to the measurement of physicochemical properties of the final pyrolysis products. In order to reduce the gas and solid fractions with corresponding increasing of condensable products, the transposition of thermal and kinetic information provided by thermogravimetric analysis (TGA) to larger reactors is used to control of process parameters. In this experimental work the mass of samples increases from 0.05 g in the thermogravimetric analyser to 600 g in the bench scale reactor.Gas-chromatography techniques have been used to identify the chemical composition of gases (GC/TCD) and liquids (GC/FID-MS).It was established that changing the reactor scale does not result in significant differences in pyrolysis product distribution, neither in gas composition. On the other hand, the aspect and the quality of condensable fraction display a high variability. Also, the energy contained in the final valuable pyrolysis product was compared with the energy demand during the thermochemical transformation in order to evaluate the energy efficiency of the process.

Technical decomposition approach of critical to quality characteristics for Product Design for Six Sigma

AbstractProduct Design for Six Sigma (DFSS) approach is a structural and disciplined methodology driven by critical to quality characteristics (CTQs). How to identify and decompose the CTQs is the kernel part in the DFSS process. Traditional method only depends on the quality function deployment (QFD) matrix to flow down CTQs roughly. The paper puts forward a novel technical approach for CTQs decomposition from customer requirements into critical technical parameters based on the relational tree. Specifically, this approach emphasizes the systematic process and quantitative computation on quality relation weight. In order to specify the object of product DFSS, the connotation and evolution model of CTQs are created first. Then along the product development process, a decomposition measure for relational tree of CTQs is studied based on the functional and physical trees in Axiomatic Design (AD). And the quality relation weight computation of its nodes by means of Rough Set and fuzzy Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is explored. Finally, an application on a car body noise vibration harshness (NVH) improvement, as an example, is given, and the decomposition process of NVH related with the functional and physical trees as well as its node weights computation algorithm are expounded in detail. Copyright © 2009 John Wiley & Sons, Ltd.

The theoretical foundations for calculating the technical parameters for low-tension overhead electricity lines for use in telecommunications

This article presents the properties of electric power networks for use as a channel for transmitting telecommunications signals. It starts by exploring the principles and theoretical basis for calculating power lines' critical technical parameters, referring in detail to the following primary parameters: inductance, capacitance, conductance and resistance. It then deals with e secondary parameters (most useful from a telecommunications perspective): characteristic impedance and propagation constant (the attenuation constant being the latter's real component). Different topologies and low- and medium-tension aerial power line structures are verified; a mathematical model is then proposed to analyse their behaviour at high frequencies, extending to most aerial electric power distribution systems in Colombia. This work includes some of the results from previous research which was known as "Using power line telecommunications (PLT) technology for designing a solution for accessing the broadband internet in rural areas of Colombia" by the present author and the Pilot University of Colombia. The proposed mathematical model provides a tool for making theoretical calculations applicable to PLT.

Predictive screening for regulators of conserved functional gene modules (gene batteries) in mammals

BackgroundThe expression of gene batteries, genomic units of functionally linked genes which are activated by similar sets of cis- and trans-acting regulators, has been proposed as a major determinant of cell specialization in metazoans. We developed a predictive procedure to screen the mouse and human genomes and transcriptomes for cases of gene-battery-like regulation.ResultsIn a screen that covered ~40 per cent of all annotated protein-coding genes, we identified 21 co-expressed gene clusters with statistically supported sharing of cis-regulatory sequence elements. 66 predicted cases of over-represented transcription factor binding motifs were validated against the literature and fell into three categories: (i) previously described cases of gene battery-like regulation, (ii) previously unreported cases of gene battery-like regulation with some support in a limited number of genes, and (iii) predicted cases that currently lack experimental support. The novel predictions include for example Sox 17 and RFX transcription factor binding sites that were detected in ~10% of all testis specific genes, and HNF-1 and 4 binding sites that were detected in ~30% of all kidney specific genes respectively. The results are publicly available at .Conclusion21 co-expressed gene clusters were enriched for a total of 66 shared cis-regulatory sequence elements. A majority of these predictions represent novel cases of potential co-regulation of functionally coupled proteins. Critical technical parameters were evaluated, and the results and the methods provide a valuable resource for future experimental design.

Quantitative evaluation of intracellular uptake of daunorubicin in acute myeloid leukemia: a method analysis.

Critical technical parameters to establish a reliable method for quantifying the intracellular content of anthracyclines were evaluated in patients with acute myelocytic leukemia (AML); two methods were used for the isolation of leukocytes from the peripheral blood and two methods, for the extraction of daunorubicin (DNR), daunorubicinol (DOL), and doxorubicin (DOX) from these cells, followed by drug analysis using high-performance liquid chromatography (HPLC). At 0-4 degrees C the recovery of leukocytes after methylcellulose separation was low (64%). Cold hypotonic lysis gave better recovery (100%) when performed at the same temperature. After low-volume (2 ml extraction mixture) drug extraction from isolated leukocytes, the recoveries of DNR, DOL, and DOX from the cells were low, and they were inversely related to the cellularity of the sample, irrespective of the amount of drug in the cells. With high-volume extraction (5 ml extraction mixture) the recoveries were better (up to 95%), but they remained dependent on the cellularity. A correction factor accounting for these cellularity-related recoveries was applied to calculate the DNR and DOL contents of the leukocytes. Finally, using this information, plasma and cellular DNR and DOL levels were measured in seven patients with AML during their first course of remission induction therapy. The cellular DNR levels appeared to vary over a broad range and did not correlate with plasma pharmacokinetics.