Drum Revolutions Research Articles

Predicting the thickness loss and recovery of acrylic carpet pile imposed to UV exposure using artificial intelligence

One of the metrics that establishes the carpet quality is its compress and decompress behaviors. In a research, addressed later in the paper, carpet samples with the acrylic pile were exposed to the ultraviolet (UV) exposure for 0, 8, 12, 16, and 20 h. The wear test was then carried out using drum revolutions of 0, 4000, 6000, and 8000. Following that, the samples were subjected to a static stress of 700 KPa for 2 h. After removing the load, the sample thickness was measured every 2 min. Finally, the thickness loss and recovery features were determined. Now in this study, the statistical analysis demonstrated the significance of recovery time, UV exposure, and drum revolutions on the features mentioned above, and in the next step, they were modeled using an artificial neural network (ANN) structure. The genetic algorithm, particle swarm optimization, and gray wolf optimization (GWO) were applied as the alternatives to the backpropagation (BP) algorithm for updating the weights and biases of ANN. In the end, it was found that the thickness loss and recovery could be predicted with 6.92 and 9.14% errors, using ANN-GWO and ANN-BP-GWO, respectively.

Estimation of the Maximum Angular Position for Cutting Roof Rock Material

In the mining and construction industry, the picks on an excavation machine often need to cut different rock types within the same drum revolution. If a rock type is much stronger than others, cutting this type of rock will often have a significant impact on the failure rates and performance of the picks and excavation machine. Therefore, it is necessary to understand the maximum angular position for cutting this type of rock, especially when it is hard rock. The accuracy of the maximum angular position for cutting the hard rock in a drum revolution affects the accuracy of the analysis of the maximum depth of cut for cutting the hard rock. It also affects the drum balance. In this paper, a method is developed to accurately calculate the maximum angular position for hard rock cutting based on the roof rock cutting in coal mining. In some cases, a simple but approximate method can be used to estimate the maximum angular position. One such case is when the strength differences between different rock types are not significant. The comparison of the influences of the accurate results on the pick performance analysis with that of the results given by the approximate method is also conducted. It shows that when the ratio of the height of the roof rock being cut to the tip-to-center cutting radius is 0.5, the maximum depth of cut in a drum revolution is less than 73 mm and the tip-to-center cutting radius is greater than 700 mm, the relative analysis error caused by the approximate method is less than 6%.

High-quality recycled concrete aggregates developed through an integrated thermomechanical approach

This study demonstrates an integrated thermomechanical treatment process to produce high quality recycled concrete aggregate (RCA) for structural concrete. RCA is mechanically treated after 90 min of heating at 250 °C in this process. The material properties of RCA produced through 15 combinations of charges and drum revolutions are compared using a statistical method. The highest ranking of an RCA identifies it as a high-quality class. Concrete composed of 100% RCA (recycled aggregate concrete, RAC) has 1.7% higher compressive strength than natural aggregate concrete (NAC). RAC has tensile and flexural strengths of 0.95 and 1.03 in fraction of NAC. RAC meets durability criteria such as UPV greater than 4.4 km/s, rapid chloride ion penetration test (RCPT) less than 1000 C, electrical resistivity greater than 208 Ohm-m, and sorptivity closer to NAC. Water absorption and abrasion resistance are similar to or superior to those of NAC. Coherent and uniform surface morphology of RCA enhances the ITZ microstructure in RAC.

Sustainable development of recycled concrete aggregate through optimized acid-mechanical treatment: A simplified approach

Present research develops an optimized acid-mechanical treatment for recycled concrete aggregate (RCA). RCA prepared in the laboratory jaw crusher is further soaked for 24 h in a mild acetic acid solution. Acid-soaked recycled aggregates (SR) are mechanically treated at a series of charges and drum revolutions using Los Angeles machines. A performance-based quality identification approach is used to compare acid-mechanically treated recycled concrete aggregates (SRij). The VIKOR indices (QI) for each SRij is calculated by applying a multi-criteria decision-making approach. Based on performance, three SRij with the lowest QI are selected for an experimental study. The present research achieves 71.27 MPa compressive strength for concrete composed of a SRij with the lowest QI. This strength is around 16.06% higher than concrete composed of parent aggregate. Flexural strength, split tensile strength, fracture energy, ultrasonic pulse velocity (UPV) values, rapid-chloride penetration test (RCPT) values, water absorption, and abrasion resistance are in the range of what is expected for parent aggregate concrete. The scanning electron microscope (SEM) image analysis shows that the well compacted and uniform surface morphology of aggregate strengthens the newly developed interfacial transition zone (NITZ) and old interfacial transition zone (OITZ). Acid treatment reduces microcrack lengths and widths and mechanical treatment reduces microcracks and pores by reducing adherent mortar optimally. X-ray diffraction (XRD) analysis shows the lower calcium hydroxide (CH) content in the mortar attached to the SR. A reduced CH content lowers the porosity in the adhered mortar. Thus, improved quality of attached mortar and its reduced porosity strengthen the old interfacial transition zone (OITZ) and lowers the sorptivity of the concrete than reported and almost equal to that of parent aggregate concrete.

An analysis of optimal segmented flight design in a rotary dryer

In this paper, an analysis of the optimal design for two-segmented flight is performed with the aim to obtain some practical recommendations for the design of a rotary dryer. Using a geometrical model, validated with experimental results, flight loading and unloading are studied over the range of every possible angle between the flight segments. Maximum volume carried out by the flight, the maximum discharging angle and the mean falling height of material are computed for all configurations. Influence of size ratio between segments and drum radius are also investigated. By determining the curtain filling degree and the cumulative transfer area of material over one drum revolution, we estimate what the best flight design is, in order to maximise the contact surface between material and air flow necessary to increase the dryer performance.

Investigating the role of mechanics in lignocellulosic biomass degradation during hydrolysis: Part II.

Lignocellulose breakdown in biorefineries is facilitated by enzymes and physical forces. Enzymes degrade and solubilize accessible lignocellulosic polymers, primarily on fiber surfaces, and make fibers physically weaker. Meanwhile physical forces acting during mechanical agitation induce tearing and cause rupture and attrition of the fibers, leading to liquefaction, that is, a less viscous hydrolysate that can be further processed in industrial settings. This study aims at understanding how mechanical agitation during enzymatic saccharification can be used to promote fiber attrition. The effects of reaction conditions, such as substrate and enzyme concentration on fiber attrition rate and hydrolysis yield were investigated. To gain insight into the fiber attrition mechanism, enzymatic hydrolysis was compared to hydrolysis by use of hydrochloric acid. Results show that fiber attrition depends on several factors concerning reactor design and operation including drum diameter, rotational speed, mixing schedule, and concentrations of fibers and enzymes. Surprisingly, different fiber attrition patterns during enzymatic and acid hydrolysis were found for similar mixing schedules. Specifically, for tumbling mixing, slow continuous mixing appears to function better than faster, intermittent mixing even for the same total number of drum revolutions. The findings indicate that reactor design and operation as well as hydrolysis conditions are key to process optimization and that detailed insights are needed to obtain fast liquefaction without sacrificing saccharification yields.

Failure Probability Prediction of Thermally Stable Diamond Composite Tipped Picks in the Cutting Cycle of Underground Roadway Development

The Thermally Stable Diamond Composite (TSDC) tipped pick has been developed to replace Tungsten Carbide (WC) tipped picks for hard rock cutting. Due to the material properties of TSDC, a major failure mode of TSDC tipped picks during rock cutting is random failures caused by excessive bending force acting on the cutting tips. A probabilistic approach has been proposed to estimate the failure probability of picks with this failure mode. However, there are two limitations in existing research: only one drum revolution is considered, and the variation of rock thickness is ignored. This study aims to extend the current approach via removing these limitations, based on the failure probability analysis of picks over a full cutting cycle in the underground coal mining roadway development process. The research results show that both drum advance direction and the variation of rock thickness have significant impacts on pick failure probability. The extended approach can be used to estimate pick failure probability for more realistic scenarios in real applications with improved accuracy. Although the study focused on TSDC tipped picks, the developed approach can also be applied to other types of picks.

Measurement and analysis of winding thickness variations in sectional warping process

PurposeSectional warping is the most widely used warp preparation process in weaving. Winding all warp sections with the same length and same tension is a key factor for a good quality warp preparation. It is required that winding thickness (increase in radius due to warp winding) remains the same within and between warp sections. The purpose of this paper is to investigate winding thickness variations within and between warp sections, which can lead to quality problems in woven fabrics.Design/methodology/approachA measurement system is developed and then an experimental investigation into winding thickness variations is carried out. Winding thickness is measured with respect to number of drum revolutions using a laser sensor with 20 microns resolution. The number of drum revolutions and drum angular position are measured by an incremental encoder. Both sensors are mounted on an industrial sectional warping machine. A real-time software written in C programming language collects and records the data for all sections of warp with respect to drum number of revolutions and then results are evaluated to determine winding thickness variations.FindingsResults show that warp sheet thickness starts with a higher value and it decreases up to around 30 drum revolutions and then it remains constant or decreases very slightly which can be considered as insignificant from practical point of view. Warp sheet thickness (i.e. thickness of one warp layer) fluctuates within each section up to 10 percent CV with five drum revolutions average warp sheet thickness. There are also warp sheet thickness variations between warp sections up to 3 mm.Originality/valueConsidering the short of practical research results on winding thickness variations in the literature, results of this study will be an original contribution to understanding winding thickness variation level. Also, results presented in this paper can be used to develop control algorithms for thickness control in sectional warping machines.

Research into the Possibility of Producing Single-Phase Tantalum–Hafnium Carbide by SHS

The influence of mechanical-activation (MA) conditions on the microstructure and phase composition of Ta–Hf–C reaction mixtures and products fabricated from them by self-propagating high-temperature synthesis (SHS) is investigated. The Ta–Hf–C reaction mixtures are mechanically activated in centrifugal planetary mills with various drum revolution rates. It is revealed that an increase in the drum revolution rate from 250 to 900 rpm lowers the heterogeneity scale of the reaction charge, decreases the size of coherent scattering regions of tantalum and hafnium by an order of magnitude, and leads to a rise in the degree of microdeformation of their crystal lattices by a factor of 1.5–2.0. It is established experimentally that it seems impossible to initiate an SHS reaction in the Ta–Hf–C activated mixture at initial temperature T0 < 550 K. The combustion process is implemented only at T0 = 800 K, when the adiabatic combustion temperature reaches 3274 K in mixtures treated with a revolution rate higher than 678 rpm. Single-phase carbide (Ta,Hf)C with lattice parameter a = 0.4487 nm, which corresponds to 18.0 at % dissolved HfC in TaC, is formed from reaction mixtures activated according to optimal regimes. The hafnium oxide content in products does not exceed 1%. The sample structure has high porosity (larger than 30%) and small carbide grain size (smaller than 10 μm), which makes it possible to produce the (Ta,Hf)C powder by milling the SHS product in a ball rotary mill.

I600 from the CSR test as a measure of pilot oven coke strength

ABSTRACTIn this study, I600 test results were compared with conventional drum indices. The I600 test is equivalent to the CSR I-drum test without pre-reaction of coke with CO2. The aim of this study was to determine to what extent the results of the I600 test could provide a useful indicator of the results of the commonly used coke strength indices. It was found that I600 correlated best with indices which had most similar particle size and drum revolutions. Further, significant improvement of relationship between CSR and CRI was obtained by incorporating the I600 index into the regression. Moreover, it was found that charge bulk density not only affected the values for the conventional drum indices, but it also affected the relationship between them and I600. Thus, charge bulk density must be included in regression aiming to compare drum indices especially those comparing results from tests with different number of drum revolutions.

Scaling inter‐tablet coating variability in a horizontal rotating drum

This study investigates how the drum‐to‐particle diameter ratio (D/d) affects the surface speed and interparticle coating variability in geometrically similar coaters. Discrete element method simulations were used to model particle movement in different‐sized, cylindrical drums with identical particle diameters, Froude numbers, fill volume fractions, and spray characteristics. The dimensionless streamwise surface speed profiles become increasingly symmetric as D/d increases, with the maximum speed increasing with D/d. The relationship between the maximum dimensionless speed and D/d is fit well with a power‐law expression. Interparticle coating variability decreases with the square root of the number of drum revolutions after a sufficiently large number of drum revolutions. Increasing D/d increases, in a logarithmic manner, the number of drum revolutions required to reach a given degree of coating variability. A similar logarithmic coating variability trend was observed in simulations using almond‐shaped pharmaceutical tablets, suggesting that the trend is independent of tablet shape. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3743–3755, 2017

INFLUENCE OF DRUM CHIPPER SETTING ON THE WOOD CHIPS PERFORMANCE

Recently, spread in the world many different categories of wood chipper to be convert the field trees waste to chips. In Egypt, especially in the new land farms the wastes of field trees represent an immense problem. For this reason, the wood chipper machine manufactured in small workshops scattered in the region of Dakahlia governorate. Because of the owners of these workshops, do not have experience in the design of wood chipper machines. Therefore, it immediately needed to evaluate each of the chipper design and its operation. Therefore, the aim of recent paper are to evaluate the design of offset slider crank for drum wood chipper and to evaluate operating parameter of drum chipper on wood chip removal rate (WCRR, m3/h), actual chip thickness (ACT), share plan angle (SPA), chip thickness ratio (CTR), chip reduction coefficient (CRC), size classification of wood chips (SCC) and the machine productivity. The operating parameters of the local chipper machine (model MUPM) included two wood sit positions in chipper (perpendicular of wood fiber relative to cutting drum (Per) and parallel to wood fiber (P); two cutting drum revolution (Per1=5000 rpm and Per2= 5500 rpm) two types of wood (white wood or exported and local wood or feedstock) and two moisture content (17% for white wood and 33% for feedstock).

Comparison of Conventional Sprocket Drum and Sprocket Drum with Modified Design

Abstract Seats in conventional sprocket drums are symmetrical. Due to the set general direction of sprocket drum revolutions resulting from the direction of rock transport, the wear of the seat bottoms and teeth flanks may be reduced by introducing the asymmetry of the profile of the sprocket drum seats. The proposed modification of sprocket drum seats’ profile consists of inclining the seat bottom towards the expected direction of the basic drum revolutions. The work compares the loads on the seats and teeth of a conventional drum with its profile conforming to the standard to a modified drum with an asymmetric profile of seats. For the general direction of sprocket drum revolutions, the maximum values of all forces are higher for a standard drum than for a modified drum. The profile asymmetry substantially shortens the friction path of the horizontal link front torus on the seat bottom and relative total friction work on the seat bottom and lessens the occurrence probability of the slide of the horizontal link rear torus on the tooth flank. The modification of the profile causes also the asymmetric wear of link joints. The total relative friction work is considerably reduced in the front joint as compared to a conventional drum, and the total relative friction work in the rear joint is increasing at the same time.

Useful life prediction of woolen hand-knotted carpets using multivariate multiple regression

In this study, the main purpose is to predict the useful life of woolen hand-knotted carpets using multivariate multiple regression. Thickness loss of surface pile yarns and compression toughness index were chosen as representative of the compression properties. Also, color difference index (ΔE) of pile yarns, tuft size index, and evenness of texture index were considered as representative of the appearance characteristics. Eighteen woolen hand-knotted carpet samples (symmetric knot) with different structural specifications were produced. The carpet samples were subjected to 4000, 8000, and 12000 drum revolutions (wear factor) using a Hexapod tumbler tester and functional properties of samples were investigated in original and worn out carpet samples. At first, the effective variables were selected using multivariate test, and then multivariate analysis of variance was used for evaluating the significance of obtained models. Optimal separate equations of the functional properties on hand-knotted carpets were determined through multivariate multiple regression method. Reverse model of wear factor can be considered as a proper equation to predict the useful life of carpets.

Effects of Mixing Variables on Early-Age Characteristics of Portland Cement Systems

AbstractThe performance and economy of infrastructure system is dependent on the specifications used to construct it. Good specifications contain requirements that correlate with improved performance and/or economy. There are several standards and specifications for mixing field concrete. These documents provide requirements for the mixing process. However, limited research has been performed on how mixing time and number of drum revolutions affect concrete characteristics. With advanced technologies that can delay the set and improve the workability, the current documents may not be applicable. This paper presents an assessment of pastes and mortars mixed for different times and varying number of mixer revolutions. Early-age characteristics include the assessment of time-variant ion concentration in solution, flowability, setting time, and chemical shrinkage. Results indicate that these early-age characteristics of pastes and mortars mixed in the laboratory are influenced by the mixing time and number of...

Influence of Truck Drum Revolution Count on Fresh and Hardened Concrete Characteristics

Influence of Truck Drum Revolution Count on Fresh and Hardened Concrete Characteristics

Effects of Mixing Variables on Hardened Characteristics of Portland Cement Mortars

Specifications and guidelines for ready mixed concrete (AASHTO M 157, ACI 304R, and ASTM C94) place limits on placement time, concrete temperature, number of truck drum revolutions, or a combination of the three. These limits should correlate with concrete performance—that is, if the limits are exceeded, it would be expected that an inferior product would be produced. An earlier paper investigating the effects of mixing time and number of mixer revolutions on cement pastes and mortars concluded that increased mixing time and mixer revolutions resulted in decreased flows, altered setting times, and increased shrinkage. This paper assesses the influence of mixing time and number of mixer revolutions on the hardened characteristics of lab-made mortars. Results indicate that increasing mixing time leads to higher 1-day compressive strengths but lower 28-day strengths. Results also indicate that an increased number of mixer revolutions can result in increased porosity, leading to decreased strength.

Effect of Traffic Exposure on Toughness Characteristics of Hand-Knotted Carpets

Compression performance is a major factor in determining the life wear of each carpet. The toughness of the pile surface, as one of the compression properties of carpets, changes when exposed to wear in use. The main aim of this study was to predict the toughness characteristics of the surface piles of hand-knotted carpets at different levels of traffic ex posure. Two types of hand-knotted carpet samples with symmetric and asymmetric knots and similar structural specifications were produced. A Hexapod tumbler tester was used to impose controlled worn out at different traffic exposures (drum revolutions). The samples were then tested with a tensile tester in the compression mode, and load-crush curves were obtained. The compression toughness characteristics and loss rate of toughness of the carpet samples were determined at 0 (new carpet), 4000, 8000, 12000 and 16000 revolutions of the Hexapod tumbler tester. Regression analysis was used to find the correlation between the traffic exposure (drum revolutions) and compression toughness characteristics. The results showed that knot type affects the toughness characteristics of the carpet. However, this effect is not statistically significant at the 5% level. On the other hand, different traffic exposure significantly affects the toughness characteristics at the 5% level.

Energy efficiency of belt conveyor at constant speed operation

Belt conveyor drives at the open pit mines consist of motors with large installed power. Each analysis of their energy efficiency presents an important factor for proper control to achieve better financial effects. The paper considers efficiency of each belt conveyor in the V ECS (excavator-belt convey or spreader) system at the open pit mine 'Drmno' as a function of time, determined based on measured values for the observed period of time. This paper analyses variations of efficiency depending on the load at constant speed. Conversion of electrical energy into mechanical by means of electrical motors and mechanical transmission is performed on belt conveyors. Therefore, the efficiency of drive station driven by electrical motors of multi motor drive is defined as a relation between the output mechanical power of multi motor drive and its input electrical power. Information about the motor torques is obtained from frequency converters, within integrated models which estimate the value of motor torque. Information about the belt speed is achieved by measuring the number of drive drum revolutions in certain period of time. Electrical power for supplying all consumers at the belt conveyor drive station is gained by measuring the power in the supply medium voltage cubicle.

High strain extensional rheometry of polymer melts: Revisiting and improving the Meissner design

A new extensional rheometer limited in achievable strain only by sample rupture is presented. The rheometer is based on the Meissner design of two pairs of counter-rotating rollers pulling a sample of fixed length but is small enough to fit inside the oven of a standard rotational rheometer and thus is dubbed the Meissner Extensional Rheometry Accessory (MERA). The true strain rate is calculated by visually accessing the sample during deformation using a high-speed digital camera. Extensional experiments were performed on three materials representing a wide range expected rheological behavior, a styrene-butadiene rubber blend, a linear polystyrene, and a branched low-density polyethylene. The MERA was able to accurately replicate the results of the well-known Sentmanat extensional rheometer (SER) design in terms of onset of strain-hardening and absolute transient extensional viscosity values. However, due to its design, it was possible to achieve homogeneous extensional flow up to real Hencky strains in excess of 8, which corresponds to a linear stretch in excess of 3000. By comparison, the SER is limited to one drum revolution, which corresponds to a Hencky strain of 3.5–4.0 or a maximum linear stretch of approximately 50. Previously the highest Hencky deformations reported in the literature are for the filament stretching extensional rheometer and Rheometric Scientific RME apparatus and in both cases approach 7, which corresponds to a linear stretch of approximately 1000.