Modelling and Optimizing an Open-Pit Truck Scheduling Problem

This paper addresses a special truck scheduling problem in the open-pit mine with different transport revenue consideration. A mixed integer programming model is formulated to define the problem clearly and a few valid inequalities are deduced to strengthen the model. Some properties and two upper bounds of the problem are proposed. Based on these inequalities, properties, and upper bounds, a heuristic solution approach with two improvement strategies is proposed to resolve the problem and the numerical experiment demonstrates that the proposed solution approach is effective and efficient

Extrapolating Survival from Randomized Trials Using External Data: A Review of Methods.

This article describes methods used to estimate parameters governing long-term survival, or times to other events, for health economic models. Specifically, the focus is on methods that combine shorter-term individual-level survival data from randomized trials with longer-term external data, thus using the longer-term data to aid extrapolation of the short-term data. This requires assumptions about how trends in survival for each treatment arm will continue after the follow-up period of the trial. Furthermore, using external data requires assumptions about how survival differs between the populations represented by the trial and external data. Study reports from a national health technology assessment program in the United Kingdom were searched, and the findings were combined with "pearl-growing" searches of the academic literature. We categorized the methods that have been used according to the assumptions they made about how the hazards of death vary between the external and internal data and through time, and we discuss the appropriateness of the assumptions in different circumstances. Modeling choices, parameter estimation, and characterization of uncertainty are discussed, and some suggestions for future research priorities in this area are given

Clinical and Epidemiological Investigation of TCM Syndromes of Patients with Coronary Heart Disease in China

To compare the regional differences in TCM syndromes of patients with coronary heart disease (CHD) between North and South China. A total of 624 patients with a diagnosis of CHD, confirmed by coronary angiography, were included in the comparative analysis to determine the occurrence pattern, characteristics of TCM syndrome distribution, and differences in syndrome combinations and major syndrome types (deficiency or excess) between North and South China. The incidence of CHD tended to be higher in North China (54.6%) compared with that in South China (45.4%). The proportions of patients with a qi-deficiency syndrome (83.7%), turbid phlegm syndrome (68.9%), or blood stasis syndrome (91.5%) were generally higher in the South group, while the proportion of patients with a cold congelation syndrome (7.9%) was identified to be obviously higher in the North group (P < 0.01). Moreover, compared with that in the South group, the overall frequency of syndrome combinations tended to be lower in the North group (P < 0.01); and the most common types of TCM syndrome were excess syndrome (193, 56.6%) and primary deficiency and secondary excess syndrome (244, 86.2%) in the North and South groups, respectively (P < 0.01). A regional difference does exist in the TCM syndromes of patients with CHD between North and South China, indicating that the prevention and treatment of CHD in South China should not only focus on promoting blood circulation and removing blood stasis, but also include supplementing qi and eliminating phleg

Ultra-high-resolution detection of Pb2+ ions using a black phosphorus functionalized microfiber coil resonator

A black phosphorus (BP) functionalized optical fiber sensor based on a microfiber coil resonator (MCR) for Pb2+ ion detection in an aquatic environment is presented and experimentally demonstrated. The MCR-BP sensor is manufactured by winding a tapered microfiber on a hollow rod composed of a low-refractive-index polycarbonate (PC) resin with the BP deposited on the internal wall of the rod. Based on the propagation properties of the MCR, the chemical interaction between the Pb2+ ions and the BP alters the refractive index of the ambient environment and thus results in a detectable shift in the transmission spectrum. The resonance wavelength moves towards longer wavelengths with an increasing concentration of Pb2+ ions, and the sensor has an ultra-high detection resolution of 0.0285 ppb (parts per billion). The temperature dependence is 106.95 pm/°C due to the strong thermo-optic and thermal-expansion effect of the low-refractive-index PC resin. In addition, the sensor shows good stability over a period of 15 days. The local pH also influences the sensor, with the resonance wavelength shift increasing as pH approaches a value of 7 but then decreasing as the pH value increases further due to the effect of the BP layer by H+ and OH− ions. The sensor shows the potential for high-resolution detection of Pb2+ ions in a liquid environment with the particular advantages of having a simple structure, ease of fabrication, low cost, low loss, and simple interrogation

Damage characteristics and mechanical properties of superhigh-water material consolidated body under triaxial stress

In order to study the damage characteristics of superhigh-wate consolidated body under triaxial stress state, uniaxial experiments of superhigh-water consolidated body under different curing time (1, 7, 14, 21, 28 d) were carried out. Uniaxial compression models under different curing times were established by the parallel bonding model of PFC3D, and five groups of uniaxial strength of PFC3D simulation experiment were obtained, which were consistent with the uniaxial strength of the uniaxial experiment. Statistics each simulation experiment of uniaxial compression parallel bond, mesoscopic physical and mechanical parameters in the model on the basis of the parameters under different curing time, superhigh-water consolidation triaxial compression model body, the same confining pressure and axial stress is applied, record the triaxial experiments under different curing time in the process of stress-strain curve and the force when the damage distribution chain. Analyzed superhigh-water body of consolidation in the damage characteristics of three to the stress state, the results show that: ① the superhigh-water concretion body three to the stress state of the changing rule of the ultimate strength with curing time can be represented by the Bohr boltzmann equation. When curing time is 1 to 14 days, the ultimate strength increases fastest, and the maximum ultimate strength reaches 3.1 MPa when curing time is 28 days. ② The variation rule of the degree of penetration of force chains in the triaxial compression model of superhigh-water consolidated body with curing time is as follows: within curing time of 1-28 d, the number of transverse contact force chains is 4 006, 4 561, 4 891, 5 017, 5 062, respectively. The number of longitudinal contact force chains is 4 029, 4 439, 4 716, 4 917 and 5 123. The results show that the carrying capacity of the superhigh-water consolidated body increases with the increase of curing time, and increases fastest during the curing time from 0 to 14 days, and tends to be stable during 14 to 28 days. ③ The tensile chain was used to simulate the fracture development in the triaxial compression model of superhigh-water consolidated body. The results show that the cracks concentrate on the upper and lower ends of the specimen when the curing time is 1 d. With the increase of curing time, the cracks in the middle of the specimen begin to increase and finally connect with the cracks at the upper and lower ends of the specimen

Thermodynamic entropy as an indicator for urban sustainability?

As foci of economic activity, resource consumption, and the production of material waste and pollution, cities represent both a major hurdle and yet also a source of great potential for achieving the goal of sustainability. Motivated by the desire to better understand and measure sustainability in quantitative terms we explore the applicability of thermodynamic entropy to urban systems as a tool for evaluating sustainability. Having comprehensively reviewed the application of thermodynamic entropy to urban systems we argue that the role it can hope to play in characterising sustainability is limited. We show that thermodynamic entropy may be considered as a measure of energy efficiency, but must be complimented by other indices to form part of a broader measure of urban sustainability