Cycle Time Analysis of Open Pit Mining Dump Trucks

This study demonstrates a practical cycle time analysis of dump truck haulage system of “Ukhaa Khudag” open-pit coal mine located in Umnugobi Province, Mongolia. It examines the possibility of minimizing the cycle time of the haulage system as well as factors impacting the speed of the dump truck. The current study divides the open pit mine road for the dump trucks into five sections which are bench road, ramp, surface road, dump road uphill, and dump road. Meanwhile, it investigates the influence of the length, the grade, and the rolling resistance of the road section on the cycle time. The data is analyzed using mathematical regression methods via Microsoft Excel program. For each of the five road sections, we compare the statistical calculations of three regression models: linear, quadratic and exponential;thus, a total of thirty regression models are obtained in this research. Accordingly, the cycle time for each road section is predicted by the most accountable model. The loaded and empty direction of the movement is measured and calculated for each road section, and it appears that the difference between the calculated mean value and the actual cycle time of the models is 0.82 seconds with a relative error of 2.51 percent.

Digitalization of mine operations:Scenarios to benefit in real-time truck dispatching

One of the key factors in a profitable open-pit mine is the efficiency of the waste disposal system. Using GPS-technology, the truck-dispatching decisions can be made in real-time but the chosen strategy has a crucial role. Therefore, finding the optimal dispatching strategy for truck-shovel operations is extremely important. Dispatching strategies have been reported in the literature, but the comparison of these strategies is still missing. This paper illustrates the differences between the strategies by conducting a stochastic simulation study based on the data gathered from an actual mine. The findings underline the importance of the global vision in dispatching decisions.

A discrete-event model to simulate the effect of truck bunching due to payload variance on cycle time, hauled mine materials and fuel consumption

Data collected from truck payload management systems at various surface mines shows that the payload variance is significant and must be considered in analysing the mine productivity,energy consumption,greenhouse gas emissions and associated cost.Payload variance causes significant differences in gross vehicle weights.Heavily loaded trucks travel slower up ramps than lightly loaded trucks.Faster trucks are slowed by the presence of slower trucks,resulting in‘bunching’,production losses and increasing fuel consumptions.This paper simulates the truck bunching phenomena in large surface mines to improve truck and shovel systems’efficiency and minimise fuel consumption.The study concentrated on completing a practical simulation model based on a discrete event method which is most commonly used in this field of research in other industries.The simulation model has been validated by a dataset collected from a large surface mine in Arizona state,USA.The results have shown that there is a good agreement between the actual and estimated values of investigated parameters.

Optimization of traffic signal parameters based on distribution of link travel time

In order to make full use of digital data, such as data extracted from electronic police video systems, and optimize intersection signal parameters, the theoretical distribution of the vehicle's road travel time must first be determined. The intersection signal cycle and the green splits were optimized simultaneously, and the system total travel time was selected as the optimization goal. The distribution of the vehicle's link travel time is the combined results of the flow composition, road marking, the form of control, and the driver's driving habits. The method proposed has 15% lower system total stop delay and fewer total stops than the method of TRRL(Transport and Road Research Laboratory) in England and the method of ARRB(Australian Road Research Board) in Australia. This method can save 0.5% total travel time and will be easier to understand and test, which establishes a causal relationship between optimal results and specific forms of road segment management, such as speed limits.

Independent Cycle Time Assignment for Min-max Systems

A variety of problems in digital circuits, computer networks, automated manufacturing plants, etc., can be modeled as min-max systems. The cycle time is an important performance metric of such systems. In this paper, we focus on the cycle time assignment of minimax systems which corresponds to the pole assignment problem in traditional linear control systems. For the min- max system with max-plus inputs and outputs, we show that the cycle time can be assigned disjointedly by a state feedback, if and only if the system is reachable. Furthermore, a necessary and sufficient condition for the cycle time to be assigned independently by a state feedback is given. The methods are constructive, and some numerical examples are given to illustrate how the methods work in practice.

Key Dolerite Dyke Swarms of Amazonia:U-Pb Constraints on Supercontinent Cycles and Geodynamic Connections with Global LIP Events Through Time

High-resolution U–Pb(ID-TIMS,baddeleyite)ages are presented for mafic dykes from selected swarms in two important Amazonian regions:the Carajás Province in the east,and the Rio Apa block in the southwest–areas

Optimizing Factory Performance for Unit Cost in Semiconductor Manufacturing

The integrated circuit (IC) manufacturing process is capital intensive and complex. The production process of unit product (or die, as it is commonly referred to) takes several weeks. Semiconductor factories (fabs) continuously attempt to improve their productivity, as measured in output and cycle time (or mean flow time). The conflicting objective of producing maximum units at minimal production cycle time and at the highest quality, as measured by die yield, is discussed in this paper. The inter-related effects are characterized, and a model is proposed to address this multi-objective function. We then show that, with this model, die cost can be optimized for any given operating conditions of a fab. A numerical example is provided to illustrate the practicality of the model and the proposed optimization method.

Optimization and Simulation of Plastic Injection Process using Genetic Algorithm and Moldflow

The use of plastic-based products is continuously increasing. The increasing demands for thinner products, lower production costs, yet higher product quality has triggered an increase in the number of research projects on plastic molding processes. An important branch of such research is focused on mold cooling system. Conventional cooling systems are most widely used because they are easy to make by using conventional machining processes. However, the non-uniform cooling processes are considered as one of their weaknesses. Apart from the conven- tional systems, there are also conformal cooling systems that are designed for faster and more uniform plastic mold cooling. In this study, the conformal cooling system is applied for the production of bowl-shaped product made of PP AZ564. Optimization is conducted to initiate machine setup parameters, namely, the melting temperature, injection pressure, holding pressure and holding time. The genetic algorithm method and Moldflow were used to optimize the injection process parameters at a minimum cycle time. It is found that, an optimum injection molding processes could be obtained by setting the parameters to the following values： TM=180℃; Pinj = 20MPa; Phold= 16MPa and thold=8s, with a cycle time of 14.11 s. Experiments using the conformal cooling system yielded an average cycle time of 14.19 s. The studied conformal cooling system yielded a volumetric shrinkage of 5.61% and the wall shear stress was found at 0.17 MPa. The difference between the cycle time obtained through simulations and experiments using the conformal cooling system was insignificant （below 1%）. Thus, combining process parameters optimization and simulations by using genetic algorithm method with Moldflow can be considered as valid.

3C行业中SCARA运用实践及未来展望

通过对手机、家电、PC机、笔记本电脑、服务器等EMS企业和工厂实际业务进行总结,从业务需求出发,得出了一些以SCARA为基础的智能制造生产线的标准化、智能化、通用化以及应用技术人才培养等方面的经验,以期让更多有志者加入到提升中国智能制造事业中来。

Influence of cycle time distribution on coating uniformity of particles in a spray fluidized bed by using CFD-DEM simulations

Cycle Time Distribution(CTD)plays a critical role for determining uniformity of particle coating in spray fluidized beds.However,the CTD is influenced by both geometrical structure and operating conditions of fluidized bed.In this study,a spray fluidized bed of coating process is simulated by a comprehensive Computational Fluid Dynamics-Discrete Element Model(CFD-DEM).To achieve different behaviors of CTD,some modifications are designed on a pseudo-2D internally circulating fluidized bed,which traditionally composes of a high-velocity upward bed and low-velocity downward bed.These modifi-cations include making the air distributor slope and/or laying a baffle in the downward bed.First,the CTD and evolution of particle size distribution under different bed structures are compared.The CTD directly influences the coating uniformity.By making the particles flowing along a parallel direction in the downward bed through the geometrical modifications,the CTD becomes narrower and the coating uniformity is significantly improved.Second,under the optimized bed structure,the influence of oper-ating conditions on the coating uniformity is studied.Properly increasing the fluidization gas velocity and the fluidization gas temperature and reducing the liquid spray rate can improve the coating uniformity.

A Deep Neural Network Model for Upper Limb Swing Pattern to Control an Active Bionic Leg

Leg amputations are common in accidents and diseases.The present active bionic legs use Electromyography(EMG)signals in lower limbs(just before the location of the amputation)to generate active control signals.The active control with EMGs greatly limits the potential of using these bionic legs because most accidents and diseases cause severe damages to tissues/muscles which originates EMG signals.As an alternative,the present research attempted to use an upper limb swing pattern to control an active bionic leg.A deep neural network(DNN)model is implemented to recognize the patterns in upper limb swing,and it is used to translate these signals into active control input of a bionic leg.The proposed approach can generate a full gait cycle within 1082 milliseconds,and it is comparable to the normal(a person without any disability)1070 milliseconds gait cycle.

Fatigue Reliability Analysis of Aircraft Turbine Disc under Random Loads

Due to bad working conditions and complicated structure,kinds of complicated cycle loads work on turbine disc, and it's difficult to determine the stress distribution of their equivalent load.Based on the traditional stress-strength interference model and conditional reliability,the reliability models of turbine disc without the stress distribution are established in this paper. In the range of fatigue limit, by improving fatigue life curve, the relationship between turbine disc's life probability distribution and material GH4133B's is got,and so is the relationship between life and stress.Then,on the basis of test data of smooth material test-piece from references,the fatigue life probability distribution of material testpiece is found out,and then the fatigue life probability distribution of turbine disc is confirmed. The fatigue life probability distribution of turbine disc is taken into reliability model and the reliability of turbine is analyzed disc under random loads. And this analysis result confirms the variation trend of engine's reliability.

An Improved Inventory Coordination Model in a Multi-stage Multi-customer Supply Chain

To solve the inventory coordination model in a multi-stage, multi-customer supply chain, this paper first analyzes the third model （integer powers of two multipliers at each firm） studied by Moutaz Khouja （2003）, and the authors take a numerical example to prove that the third model is irrational to miss feasible solution. Then this paper puts up a new improved model （integer multiplier at each firm）, and takes the example to prove it gives better results than the integer powers of two multipliers at each firm.

Epigenetic Enabled Normal Human Cells, Lead to <i>First Cell</i>’s Unique Division System, Driving Tumorigenesis Evolution

Normal cells must become cancer-enabling before anything else occurs, according to latest literature. The goal in this mini-review is to demonstrate special tetraploidy in the enabling process. This we have shown from genomic damage, DDR (DNA Damage Response) activity with skip of mitosis leading to diploid G2 cells at the G1 border in need of chromatin repair for continued cell cycling to the special tetraploid division system. In several studies specific methylation transferase genes were activated in normal human cells in tissue fields, containing different cell growth stages of the cancerous process. Histology studies, in addition to molecular chemistry for identification of oncogenic mutational change, were a welcome change (see below). In a study on melanoma origin, DDR also showed arrested diploid cells regaining cycling from methylation transferase activity with causation of 2n melanocytes transforming to 4n melanoblasts, giving rise to epigenetic tumorigenesis enabled First Cells. Such First Cells were from Barrett’s esophagus shown to have inherited the unique division system from 4n diplochromosomal cells, first described in mouse ascites cancer cells (below). We discovered that the large nucleus prior to chromosomal division turned 90° relative to the cytoskeleton axis, and divided genome reductive to diploid, First Cells, in a perpendicular orientation to the surrounding normal cells they had originated from. This unique division system was herein shown to occur at metastasis stage, implying activity throughout the cancerous evolution. Another study showed 4-chromatid tetraploidy in development to B-cell lymphoma, and that such cancer cells also proliferated with participation of this unusual division system. Such participation has long been known from Bloom’s inherited syndrome with repair chiasmas between the four chromatids, also an in vitro observation by us. Our cytogenetic approach also revealed that they believed mitotic division in cancer cells is wrong because such cell divisions were found to be from an adaptation between amitosis and mitosis, called amitotic-mitosis. Amitosis means division without centrosomes, which has long been known from oral cancer cells, in that MOTCs (microtubule organizing center) were lacking centrioles. This observation calls for re-introduction of karyotype and cell division studies in cancer cell proliferation. It has high probability of contributing novel approaches to cancer control from screening of drugs against the amitotic-mitotic division apparatus.

Effect of operational and geometric parameters on the hydrodynamics of a Wurster coater:A CFD-DEM study

A coupled CFD-DEM method was used to study the hydrodynamics of a Wurster coater.Firstly,the CFD part of the model was validated by the accurate prediction of the pressure drops over a pseudo-2D fluidized bed under various gas velocities.The effect of gas velocity,gap height,tube length and batch volume of the particles on the cycle time and the residence time of the particles was thoroughly investigated.The central jet gas velocity ui was found to speed up the particle cycle but undermine the coating efficiency.The gas velocity at the horizontal transport zone u2 was able to promote the horizontal transport of the particles but should not be too high,otherwise,it would obstruct the normal falling back of the particles in the downward zone.Big gap heights would decrease the coating efficiency but tube length had little impact on that.The increment of batch volume would commonly abase the cycle time and the working efficiency under a given u1.The de-fluidization problem arose when the batch volume increased to 550 mL.However,this problem could be swept out by the optimization of u1 and u2.In a mixture of different sizes,the coarse particles enjoyed higher coating efficiency and could travel closer to the nozzles.This may shield the fine particles from getting enough coating liquids,and thus coarse particles and fine particles were not recommended to get coated in the same batch.

A prospective study to evaluate the efficacy of an intracardiac electrogram-based atrioventricular and interventricular intervals optimization method in cardiac resynchronization therapy

Background Cardiac resynchronization therapy （CRT） with biventricular pacing improves cardiac function,functional capacity and quality of life in selected patients with heart failure.The current study aimed to evaluate the efficacy of the intracardiac electrogram （IEGM）-based optimization method,QuickOptTM,in Chinese patients treated with CRT.Methods Aortic time velocity integrals （AVTI） achieved at the sensed atrioventricular （AV）,paced AV and interventricular （VV） interval settings recommended by both QuickOptTM and standard echocardiographic optimization were measured in 101 patients.Consistency and the strength of the relationship between the two timing cycle optimization methods were assessed by intra-class correlation coefficient （ICC）.Results The ICC showed good agreement and correlation with what the AVTI achieved at the optimal sensed AV （ICC=0.9683 （0.9535-0.9785））,paced AV （ICC=0.9642 （0.9475-0.9757）） and VV （ICC=0.9730 （0.9602-0.9817）） interval settings determined by the two optimization methods.The average time required by echocardiographic optimization and by QuickOptTM were （78.32±32.40） minutes and （1.98±1.64） minutes respectively （P 〈0.0001）.Conclusion The QuickOptTM algorithm provides a quicker,simpler and reliable alternative to the standard method for timing cycle optimization.（ClinicaITrial.gov Reference Number：NCT00918294）

Microstructure characterization and HCF fracture mode transition for modified 9Cr-1Mo dissimilarly welded joint at different elevated temperatures

The high cycle fatigue（HCF） tests of modified 9 Cr-1 Mo dissimilarly welded joint were carried out at different elevated temperatures and the fracture mechanism was systematically revealed. The fatigue strength at 108 cycles based on S-N curve can be estimated as a half of weld joint＇s yield strength for all conducted temperatures, which can be a reliable criterion in predicting the fatigue life. The results show that the inter-critical heat affected zones（IC-HAZs） of both sides are the weak zones due to their low hardness and inferior fatigue resistance property. HAZ of COST-FB2（BM2） is the weakest zone at room temperature due to the existence of numerously distributed defects and the initiation of cracks, either in the surface or interior zone, impacting a crucial effect on the fatigue life of the joint. While at elevated temperatures, fatigue life was controlled mostly by the intrusion-extrusion mechanism at the specimen surface under high stress level and subsurface non-defect fatigue crack origin（SNDFCO） from the interior material under low stress amplitude. With increasing temperature, more and more fatigue failures began to occur at the HAZ of COST-E（BM1） due to its higher susceptibility of temperature. Besides, it is found that the-ferrite in the BM1 has no harm to the HCF behavior of the joint at the conducted temperatures.

Compressive Mechanical Characteristics of Multi-layered Gradient Hydroxyapatite Reinforced Poly(Vinyl Alcohol) Gel Biomaterial

Functional gradient materials provided us a new concept for artificial articular cartilage design with gradient component and gradient structure where one side of the material is high free water content thereby providing excellent lubrication function and the opposite side of the material is high hydroxyapatite content, thereby improving the bioactivity of the material and stimulating cell growth. The goal of the present study was to develop a multi-layered gradient HA/PVA gel biocomposites through layer-by-layer casting method combing with freeze/thaw cycle technology. The various influence factors on the compressive strength and modulus of the multi-layered gradient biocomposites were investigated. The results showed that the compressive mechanical characteristics of the biocomposites were similar to that of natural articular cartilage. Both the compressive strength and modulus of the multi-layered gradient HA/PVA gel biocomposites increased exponentially with the rise of compressive strain ratio. Both the compressive strength and average compressive modulus of the biocomposites improved with the rise of freeze/thaw cycle times and total concentration of HA particles in the biocomposites, but they showed decreasing tendency with the rise of HA concentration difference between adjacent layers.