Mathematical programming for single- and multi-location non-stationary inventory control

Stochastic inventory control investigates strategies for managing and regulating inventories under various constraints and conditions to deal with uncertainty in demand. This is a significant field with rich academic literature which has broad practical applications in controlling and enhancing the performance of inventory systems. This thesis focuses on non-stationary stochastic inventory control and the computation of near-optimal inventory policies for single- and two-echelon inventory systems. We investigate the structure of optimal policies and develop effective mathematical programming heuristics for computing near-optimal policy parameters. This thesis makes three contributions to stochastic inventory control. The first contribution concerns lot-sizing problems controlled under a staticdynamic uncertainty strategy. From a theoretical standpoint, I demonstrate the optimality of the non-stationary (s,Q) form for the single-item single-stocking location non-stationary stochastic lot-sizing problem in a static-dynamic setting; from a practical standpoint, I present a stochastic dynamic programming approach to determine optimal (s,Q)-type policy parameters, and I introduce mixed integer non-linear programming heuristics that leverage piecewise linear approximation of the cost function. The numerical study demonstrates that the proposed solution method efficiently computes near-optimal parameters for a broad class of problem instances. The second contribution is to develop computationally efficient approaches for computing near-optimal policy parameters for the single-item single-stocking location non-stationary stochastic lot-sizing problem under the static-dynamic uncertainty strategy. I develop an efficient dynamic programming approach that, starting from a relaxed shortest-path formulation, leverages a state space augmentation procedure to resolve infeasibility with respect to the original problem. Unlike other existing approaches, which address a service-level-oriented formulation, this method is developed under a penalty cost scheme. The approach can find a near-optimal solution to any instance of relevant size in negligible time by implementing simple numerical integrations. This third contribution addresses the optimisation of the lateral transshipment amongst various locations in the same echelon from an inventory system. Under a proactive transshipment setting, I introduce a hybrid inventory policy for twolocation settings to re-distribute the stock throughout the system. The policy parameters can be determined using a rolling-horizon technique based on a twostage dynamic programming formulation and a mixed integer linear programme. The numerical analysis shows that the two-stage formulation can well approximate the optimal policy obtained via stochastic dynamic programming and that the rolling-horizon heuristic leads to tight optimality gaps

Dynamic Succession of Microbial Communities in Soybean Paste Made with Broomcorn Millet as an Additive and Its Correlation with Flavor and Nutritional Properties during the Brewing Process

To obtain a full understanding the quality and microbial characteristics of soybean paste made from a mixture of soybean and broomcorn millet flour, its physicochemical properties (amino nitrogen and nitrite), and total phenols (TP), γ-aminobutyric acid (GABA), free amino acids (FAAs), volatile compounds, and microbial community composition were investigated. The results showed that the amino nitrogen content increased to 0.71%, and the nitrite content decreased to within the standard range (1.37 mg/kg). The contents of TP, key FAAs and volatile compounds increased significantly during the fermentation process. The core microbial communities included Enterobacter, Pseudomonas, Stenotrophomonas, Aspergillus, and Alternaria. The results of correlation analysis confirmed that bacteria (Bacillus, Knoellia, and Blastococcus) and fungi (Epicoccum and Saccharomyces) played a significant role in the bioactivity changes and flavor generation in soybean paste. This study will be of great significance for understanding the quality and flavor of novel soybean paste made with cereal flour as an additive

Gender differences in the clinical management of patients with angina pectoris: a cross-sectional survey in primary care

Non peer reviewedPublisher PD

Structure Design and Calibration of INS for Distributed POS Technology

With the development of science and technology, position and orientation system (POS) technology has become an important tool for airborne earth observation system, and plays an important role in both military and civil fields. The calibration of the device directly affects the accuracy of inertial navigation. Therefore, the paper designs a compact dual mode navigation system with high and low precision, which can be used in distributed POS system. Firstly, the status of IMU calibration technology is introduced. Then it introduces the working principle, structure design and layout design of fiber optic gyroscope (FOG) combination. Finally, the calibration experiment verifies that the designed FOG combination system meets the performance index

Analysis of Distributed Measurement Method for Array Antenna Position

The measurement of the phase center of the airborne array antenna can directly affect the accuracy of the Earth observation system. However, the relationship between the relative motion of each sub-antenna cannot be accurately measured because of the adverse environment of the airborne platform. Therefore, it is necessary to find a suitable method to measure the motion parameters of distributed antennas and the phase center of each element antenna accurately in order to improve the imaging resolution of the Earth observation system. Distributed position and orientation system (POS) technology has high precision, but its measurement error will accumulate with time. So it needs to transfer and align continuously to achieve high-precision measurement. The paper introduces the distributed measurement method of measuring the array antenna position based on the combination of fiber Bragg grating (FBG) sensing technology and POS technology on the aircraft wing. The paper first introduces the technical scheme and principle, then carries out the structural design and method analysis. Next, the structural strength of the experimental model is checked and summarized

Fiber Bragg Gratings Sensors for Aircraft Wing Shape Measurement: Recent Applications and Technical Analysis

The safety monitoring and tracking of aircraft is becoming more and more important. Under aerodynamic loading, the aircraft wing will produce large bending and torsional deformation, which seriously affects the safety of aircraft. The variation of load on the aircraft wing directly affects the ground observation performance of the aircraft baseline. To compensate for baseline deformations caused by wing deformations, it is necessary to accurately obtain the deformation of the wing shape. The traditional aircraft wing shape measurement methods cannot meet the requirements of small size, light weight, low cost, anti-electromagnetic interference, and adapting to complex environment at the same time, the fiber optic sensing technology for aircraft wing shape measurement has been gradually proved to be a real time and online dynamic measurement method with many excellent characteristics. The principle technical characteristics and bonding technology of fiber Bragg grating sensors (FBGs) are reviewed in this paper. The advantages and disadvantages of other measurement methods are compared and analyzed and the application status of FBG sensing technology for aircraft wing shape measurement is emphatically analyzed. Finally, comprehensive suggestions for improving the accuracy of aircraft wing shape measurement based on FBG sensing technology is put forward