Probable Error Research Articles

Flow pattern transition and coal beneficiation in gas solid fluidized bed with novel secondary distributor

Gas solid fluidized bed (GSFB) is an effective method of dry coal separation. In this study, porous sponge was introduced into a typical gas solid fluidized bed as secondary air distribution layer (PSFB) to stabilize the fluidized bed layer. The difference between PSFB and GSFB in flow pattern transition process was studied. Compared with GSFB, the minimum gas velocity and bed density fluctuation decreased while bed expansion ratio increased in PSFB. Furthermore, the distribution of bubble phase and emulsion phase were more homogeneous in PSFB. Under the operational conditions, the results of coal preparation in a PSFB showed that the ash content of clean coal was 10.25% .The probable error (E) was 0.095 g/cm3, indicating that PSFB could provide a novel way for a good performance of dry coking coal beneficiation.

Novel method of air distributor design for enhancing bed stability and reducing impurities in gas–solid fluidized bed system

ABSTRACTCoal plays a key role in the economic development of China. It is greatly significant to improve the efficient use of coal through high-efficiency dry separation. In this paper, a porous sponge was used to optimize the air distributor, and its fluidization characteristics were studied. Response surface methodology was used to study the collaborative optimization effects of gas velocity, separation time, and bed height on the fine coal separation. Gas velocity was the main factor which affects separation efficiency. When separation is in operation parameters, the yield and ash content were 65.48 and 10.89% as to the clean coal product and 9.24 and 80.47% as to the gangue product, respectively. Furthermore, the yield and ash content of middlings were 25.29 and 20.32%, respectively. The probable error, E, values were between 0.085 and 0.100 g/cm3. Using XRF and FTIR analysis, it was observed that the harmful elements and impurities in coal were reduced during the separation process.

Size by Size Separation Characteristics of a Coal Cleaning Jig

Jigging is essentially a cleaning process to separate particles of different relative densities. Usually the jig feed is narrowly sized, however the definition of settling velocity indicates that particle size possibly plays certain role in the process of separation. Limited work is available in published literature on the separation characteristics of constituent size fractions of the feed that has been subjected to jigging. The present communication examines size by size separation characteristics of a Batac jig cleaning metallurgical coal. The characteristics have been measured by Probable Error in Separation, Imperfection and Organic Efficiency. Effect of NGM on the separation characteristics, if any, has also been investigated.

Characteristic gas velocity and fluidization quality evaluation of vibrated dense medium fluidized bed for fine coal separation

In order to remove incombustible impurity minerals, a vibrated dense medium fluidized bed (VDMFB) can be adopted for fine coal dry separation, while Geldart B magnetite powder can serve as the medium. The influence of vibration on characteristic gas velocity in flow pattern transition stage was experimentally investigated at a vibration amplitude range of 0.5–4 mm and frequency range of 5–35 Hz. The experimental results demonstrate that at a low frequency (f < 10 Hz), the vibration effect results in a denser bed and a slightly smaller initial fluidization gas velocity. As the vibration frequency increases to a level similar to the bed’s natural frequency, the minimum fluidization gas velocity reduces sharply. The minimum fluidization gas velocity correlation in the VDMFB is obtained by means of theoretical deduction and experimental data fitting. Furthermore, a method is proposed for evaluating the effects of vibration on improving fluidization quality. Based on that, using the coal separation probable error Ep⩽0.1 as the evaluation index, a suitable effective operating gas velocity range for coal separation under different vibration parameters is determined. The ratio of the boundary operating gas velocity to Umfc is 0.67–2.28. Thus, a uniform and stable fluidization environment is provided for dry fine coal separation.

Quad-level cell NAND design and soft-bit generation for low-density parity-check decoding in system-level application

QLC (Quad-Level Cell) NAND flash will be one of the future technologies for next generation memory chip after three-dimensional (3D) TLC (Triple-Level Cell) stacked NAND flash. In QLC device, data errors will easily occur because of 24 data levels in the limited voltage range. This paper studies QLC NAND technology which is 4 bits per cell. QLC programming methods based on 16 voltage levels and reading method based on “half-change” Gray coding are researched. Because of the probable error impact of QLC NAND cell’s voltage change, the solution of generating the soft information after XOR (exclusive OR) the soft bits by internal read mechanism is presented for Low-Density Parity-Check (LDPC) Belief Propagation (BP) decoding in QLC design for its system level application.

Sliding Mode Control for Three-Phase Quasi-Z-Source Inverter

In this paper, a novel multiobjective control strategy for the three-phase quasi Z-source inverter (q-ZSI) is proposed. A sliding mode control (SMC)-based controller is proposed to regulate inductor current through shoot-through ratio, and DC-link voltage reference is considered as an additional control input to keep q-ZS network capacitor voltage at a desired constant level. The load current is regulated by a proportional resonant controller whose output is then divided by DC-link voltage reference to obtain a modulation signal. With these three control inputs, the system is no longer underactuated, thus to eliminate probable steady-state error, which always happens in the underactuated system. The SMC-based controller for inductor current has the advantages of easy implementation, strong robustness, fast response, and low current ripple. The capacitor voltage is kept constant by the proportional integral-based variable DC-link voltage reference theme with negligible steady-state error and load current is pure sinusoidal with low THD. Simulations and experimental results both verify the effectiveness of the proposed control strategy.

Nvestigating the Effects of Behavioral Factors on Investment Performance in Nigerian Capital Market

The study sought to investigate the effect of behavioral factors, including prospects on investment performance in Nigerian capital market using a cross sectional survey design was employed. A sample size of 160 staff was drawn from a population of 225 staff of active stock brokerage firms in Abuja. Data were collected by way of administered questionnaire and the analysis was done using a simple percentage and multiple regression analysis with the aid of SPSS the relationships between the behavioral factors and investment performance. The findings show that that there is a positive significant relationship between prospect factor and investment performance, It is recommended that investors should carefully consider and carry out research before making investment decisions and should not be carried away by their earlier loss for their future investment decisions. Emphasis should be made on probable cognitive errors such as representativeness, hindsight, illusion of control and availability biases and emotional biases such as regret aversion and over optimism. Also, training programs that create investor awareness in terms of the capacity to point out and protect against cognitive errors and emotional biases that lead to bad investment choices should be offered to prospective individual investors

Performance Optimization of a New Air Table and Flip-flow Screen for Fine Particle Dry Separation

ABSTRACT The mining industry has seen increased efforts toward achieving dry mineral separation owing to current and projected water scarcity and environmental problems associated with conventional wet processing methods. Commercially available dry coal separation technologies such as air tables and air jigs have proven effective in cleaning only the +6.35 mm while the −6.35 mm comprised of coal and impurities is discarded or used without further cleaning. To address this issue, a new density-based dry separator named SIU Airtable was developed. The main objective of this study was to evaluate the fine coal (6.35 × 1 mm) dry cleaning performance of the developed air table. The study also sought to evaluate the dry screening performance of the Liwell flip-flow screen to achieve efficient size separations at 1 and 2 mm. Two different Illinois No. 6 coal samples were used to optimize the new air table by varying its operating variables. The analysis of separation efficiency showed similar trends for both coal samples based on the cut point density (SG50) and probable error (Ep). Additionally, separation efficiency was significantly higher for the 6.35 × 3.36 mm size fraction and reduced when the size range was broadened to 6.35 × 1 mm. Product coal ash of 13.8–14.5% and tailings ash of 52.9–59.7% were achieved from the feed ash of 31–36%. Screening experiments on the Liwell flip-flow screen showed an efficiency of 88.7% and 85.1% achieved for the 1-mm and 2-mm polyurethane panels, respectively.

Analysis, optimization and prototyping of a parallel RCM mechanism of a surgical robot for craniotomy surgery

PurposeRemoving the bone flap is a compulsory step in open skull surgeries and is very cumbersome and time-consuming. Exerting large forces during the milling and cutting of the skull renders the surgeon exhausted and consequently increases probable errors in further task of manipulating the sensitive brain tissue. This paper aims to present the development of a robotic system capable of perforating and cutting the required bone flap without restraining the surgeon.Design/methodology/approachFor the purpose of optimization, the target workspace is estimated by 3D modeling of the sample skull and bone flaps of targeted surgeries. The optimization considers kinematic performance matrices and the extracted workspace requirements by assigning scores to each possible design and finally selects the design with highest score.FindingsThe design utilizes a parallel remote center of motion mechanism. Coordinating the remote center of motion (RCM) of the mechanism with the center of a sphere which circumscribes the skull, the milling tool is always nearly perpendicular to the skull bone. The paper presents the concept design, optimization criteria and finally the optimal design of the robot and the fabricated prototype. Tests indicate that the prototype is able to sweep the target workspace and to exert the required forces for bone milling.Originality valueThe workspace requirements of the craniotomy/craniectomy surgeries are investigated and converted into one quantitative target workspace. An optimized design for a surgical robot is developed which satisfies the workspace requirements of the targeted surgeries.

Temperature effect on various biooils physical parameters

The article deals with thermal and rheological properties of two selected biooils (PL 64S – sample No. 1, and PL 04N – sample No. 2). For thermal parameters measurements, Hot wire method was used, for detection of rheological parameters rheometer Anton Paar MCR 102 was used and the density was measured by densimeter DM 40. For both biooil samples, two series of thermophysical parameters measurements were made. In the first series thermal conductivity and thermal diffusivity were measured at constant laboratory temperature. The second series was focused on identification of thermophysical parameters changes during temperature stabilisation. The parameters as dynamic viscosity, kinematic viscosity and density were measured in the temperature range (20–50°C). For samples with constant temperature basic statistical characteristics were calculated – standard deviation and probable error in %. For relations of thermal and rheological parameters to temperature nonlinear dependencies were obtained. The polynomial functions of the second degree were used for thermal parameters and exponential functions for rheological parameters.

A posteriori error estimates in voice source recovery

The inverse problem of voice source pulse recovery from a segment of a speech signal is under consideration. A special mathematical model is used for the solution that relates these quantities. A variational method of solving inverse problem of voice source recovery for a new parametric class of sources, that is for piecewise-linear sources (PWL-sources), is proposed. Also, a technique for a posteriori numerical error estimation for obtained solutions is presented. A computer study of the adequacy of adopted speech production model with PWL-sources is performed in solving the inverse problems for various types of voice signals, as well as corresponding study of a posteriori error estimates. Numerical experiments for speech signals show satisfactory properties of proposed a posteriori error estimates, which represent the upper bounds of possible errors in solving the inverse problem. The estimate of the most probable error in determining the source-pulse shapes is about 7-8% for the investigated speech material. It is noted that a posteriori error estimates can be used as a criterion of the quality for obtained voice source pulses in application to speaker recognition.

Effect of vibration on the separation efficiency of oil shale in a compound dry separator

Oil shale is a special energy source between coal and petroleum and is a potential alternative energy source. However, during oil shale mining, a large amount of Inorganic mineral impurities is produced. Thus, the grade of the oil shale is reduced, it can be effectively utilized by performing beneficiation through physical sorting to reduce impurities and upgrade the oil content. In this paper, the physical properties of oil shale were analyzed, beneficiation of 50-0 mm oil shale using a compound dry separator was proposed. The effect of vibration on the beneficiation process was emphatically investigated. The law of force between particles in different sorting areas and the effects of amplitude, frequency and angle of vibration on the energy law of different sorting area are systematically analyzed, The optimum operation parameters were obtained, and the sorting test was carried out. The results showed that when the force uniformity between the concentrate area and the tailings area is the best and the fluctuation range is minimum and the peak force of the particles corresponding to the concentrate area and the tailings area is 8.24 mN, 10.57 mN, 12.34 mN, 8.13 mN under the amplitude is 3.8–4.0 mm, frequency is 38-39hz. When frequency is 38 hz, Amplitude is 3.9 mm, the vibration acceleration of the concentrate area and tailings area are 24.78 m/s2, 17.89 m/s2, and the concentrate area was the main separation area, and the tailings area was mainly used to transport and discharge gangue. The separation tests were carried out under the optimum vibration parameters (A = 3.9 mm, f = 38hz, θ = 45°), The yields and oil content of the concentrate are 34.63% and 11.03%, while those of tailings are 65.37% and 1.01%, and the separating accuracy (probable error E) is 0.14 g/cm3, the actual separation density is 2.33 g/cm3. The vibration plays an important role in the compound dry separating oil shale efficiently.

Recent progresses about statistical declaration and probable error for surface drag force of chemically reactive squeezing flow with temperature dependent thermal conductivity

This communication addresses unsteady squeezing flow of second grade liquid. NonFourier heat flux model is implemented to discuss heat transfer features subject to heat generation/absorption. Homogeneous–heterogeneous reactions are addressed. Firstly, the problems are nondimensionalized by suitable variables and then solutions for strong nonlinear systems are presented. Convergence region is particularly determined for obtained solutions. Statistical declaration and probable error for drag force are computed. Velocity is found to decay for larger estimation of fluid parameter while thermal and concentration fields are enhanced for higher heat generation and squeezing parameters.

Current progresses about probable error and statistical declaration for radiative two phase flow using Ag[sbnd]H2O and Cu[sbnd]H2O nanomaterials

Here modeling and computations are presented to introduce the novel concept of statistical declaration and probable error for radiative flow between two stretchable rotating disks. Effects of Joule heating and thermal radiation are accounted. Homogenous and heterogeneous reactions are also implemented. The thermophysical characteristics of nanofluids are scrutinized using silver and copper nanoparticles. Statistical declaration and probable error for coefficient of skin friction and heat transfer rate are calculated. System of nonlinear ordinary differential equations is obtained by using appropriate variables. Convergent solutions of the involved problems are obtained and discussed. Skin friction coefficient and Nusselt number are calculated and discussed. Radial and axial velocities have opposite impact for stretching parameters of lower and upper disks. Concentration decays for both Schmidt number and homogeneous reaction variable. Coefficient of skin friction is less for larger rotational parameter at both disks. Opposite behavior of heat transfer rate is observed at lower and upper disks for increasing Eckert number. For limiting cases comparisons with previously available results [23,52,53] in the literature are made and an excellent agreement is noticed.

Determination of constituents receipt Kakhovka Reservoir water balance

The study of the reservoirs is of great scientific interest and is of practical importance for the solution of problems of rational use and protection of water resources. The paper describes the latest reservoir in the cascade of Dnipro Kakhovka Reservoir and its component of water balance. The methods of determining the components of the water balance that were once offered the Kakhovka hydrometeorological observatory are submitted. Great attention is drawn to the surface flow of water into the reservoir from unexplored rivers, which is determined by the method of analogy. The probable error of this method, in turn, is equal to for monthly values 30-50% and annual – 10-20%. So, there is provided somewhat different a method for determining the surface flow using the curve of security component amount of annual precipitation, maps of the norm runoff and tables SNiP 2.01.14.83. The proposed method simplifies and accelerates the process of calculating the amounts of surface water flow in unexplored rivers to Kakhovka reservoir.

Dry beneficiation of fine coal using planar air jets

In this study, a novel separation method deploying planar air jets was proposed for the dry beneficiation of −6+2mm fine coal and a laboratory separation equipment was established. The separation principle of this method was based on the separation of horizontal movement trajectories of coal particles depending on the density differences when passing through the flow field of a planar air jet. The effects of operational parameters, including air jet velocity, air jet angle, feeding height, and feeding rate, on the beneficiation performance were experimentally studied and the results showed that all of these parameters had significant effects to varying degrees. The results also showed that the separation accuracy, the probable error E, is 0.2, indicating that this method can effectively beneficiate fine coal in a dry way.

Intensification of the density stability in the air dense medium gas–solid fluidized bed based on a binary dense media

Intensification of the density stability in the air dense medium gas−solid fluidized bed is significantly important to the separation efficiency of this density-based separator. A binary dense media composed of the magnetite powder and quartz sand was used to achieve the intensification of the density stability. The fluctuation characteristics of the bed pressure gradients were investigated to seek for the optimum composition of binary dense media. The weight proportion of quartz sand in the binary dense media should not exceed 30%. The stability and uniformity of the bed density along the axial and radial directions of fluidized bed were experimentally investigated. The results indicated that the weight proportion of quartz sand should be controlled within 10%–20%, and the fluidization number should be adjusted from 1.5 to 1.6. A reliable mathematical model was established to predict the bed density. The calculation and measurement results agreed well, which validated the prediction accuracy. With a 10% weight proportion of quartz sand, the ash content of −13+6mm sized coal was decreased from 33.35% to 11.55% with a clean coal yield of 69.48% at a fluidization number of 1.6. A satisfactory probable error value of 0.095g/cm3 indicated notable separation performance.

Quantification of Representative Ciguatoxins in the Pacific Using Quantitative Nuclear Magnetic Resonance Spectroscopy.

The absolute quantification of five toxins involved in ciguatera fish poisoning (CFP) in the Pacific was carried out by quantitative 1H-NMR. The targeted toxins were ciguatoxin-1B (CTX1B), 52-epi-54-deoxyciguatoxin-1B (epideoxyCTX1B), ciguatoxin-3C (CTX3C), 51-hydroxyciguatoxin-3C (51OHCTX3C), and ciguatoxin-4A (CTX4A). We first calibrated the residual protons of pyridine-d5 using certified reference material, 1,4-BTMSB-d4, prepared the toxin solutions with the calibrated pyridin-d5, measured the 1H-NMR spectra, and quantified the toxin using the calibrated residual protons as the internal standard. The absolute quantification was carried out by comparing the signal intensities between the selected protons of the target toxin and the residual protons of the calibrated pyridine-d5. The proton signals residing on the ciguatoxins (CTXs) to be used for quantification were carefully selected for those that were well separated from adjacent signals including impurities and that exhibited an effective intensity. To quantify CTX1B and its congeners, the olefin protons in the side chain were judged appropriate for use. The quantification was achievable with nano-molar solutions. The probable errors for uncertainty, calculated on respective toxins, ranged between 3% and 16%. The contamination of the precious toxins with nonvolatile internal standards was thus avoided. After the evaporation of pyridine-d5, the calibrated CTXs were ready for use as the reference standard in the quantitative analysis of ciguatoxins by LC/MS.

Modern developments about statistical declaration and probable error for skin friction and Nusselt number with copper and silver nanoparticles

This communication explores simultaneous impact of Joule heating and viscous dissipation in radiative flow of viscous fluid by a stretching cylinder. The thermal characteristics of nanofluids are explored using copper and silver nanoparticles. Homogeneous and heterogeneous reactions are accounted. Statistical declaration and probable error for skin friction and Nusselt number are computed. The nonlinear differential systems are solved using Euler’s Explicit Method (EEM). The effects of emerging variables for velocity, temperature, concentration, skin friction and Nusselt number are examined extensively. It is noticed that the magnetic parameter decays the fluid velocity for copper-water and silver-water nanomaterials. Radiative heat transfer and viscous dissipation lead to an increase in the fluid temperature and thermal boundary layer thickness.

Deep Neural Network Probabilistic Decoder for Stabilizer Codes

Neural networks can efficiently encode the probability distribution of errors in an error correcting code. Moreover, these distributions can be conditioned on the syndromes of the corresponding errors. This paves a path forward for a decoder that employs a neural network to calculate the conditional distribution, then sample from the distribution - the sample will be the predicted error for the given syndrome. We present an implementation of such an algorithm that can be applied to any stabilizer code. Testing it on the toric code, it has higher threshold than a number of known decoders thanks to naturally finding the most probable error and accounting for correlations between errors.