Efficient aircraft spare parts inventory management under demand uncertainty

In airline industries, the aircraft maintenance cost takes up about 13% of the total operating cost. It can be reduced by a good planning. Spare parts inventories exist to serve the maintenance planning. Compared with commonly used reorder point system (ROP) and forecasting methods which only consider historical data, this paper presents two non-linear programming models which predict impending demands based on installed parts failure distribution. The optimal order time and order quantity can be found by minimizing total cost. The first basic mathematical model assumes shortage period starts from mean time to failure (MTTF). An iteration method and GAMS are used to solve this model. The second improved mathematical model takes into account accurate shortage time. Due to its complexity, only GAMS is applied in solution methodology. Both models can be proved effective in cost reduction through revised numerical examples and their results. Comparisons of the two models are also discussed

FOOT FUNCTION ASSESSMENT THROUGH KINEMATIC AND KINETIC ANALYSIS

The purpose of this study was to investigate toes’ function while performing barefoot and shod running between habitually unshod and shod runners. Seven habitually male shod runners and six habitually male barefoot runners participated the running test. Kinematic and kinetic analysis were synchronously conducted. The habitually unshod runners showed significantly higher ankle eversion-to-inversion angle in the pushing-off phase than habitually shod runners. And forefoot loading reduced as the big toe of habitually unshod runners pushing ground under shod condition, with similar function of other toes among habitually shod runners. It is noted that the work of big toe and other toes lead to the decreased loading to the forefoot. This might be beneficial for the prevention of foot injuries, like plantar fasciitis and metatarsal fatigue fracture

An Optimization Approach for Pricing Analysis on a Bank Wealth-Management Equity Structured Product

This paper researches on the pricing and design of a certain stock-type structured product. Firstly, a semi-analytic pricing model is deduced by discounting the payoff function of the product. Secondly, the difference between publishers\u27 and investors\u27 required rate of return is explained with market segmentation theory when estimating the pricing model’s parameters, which defines the cost and sale price of a product. Finally, with sensitivity analysis, it is concluded that publishers can increase their profits by extending the due date of the product or publishing it with relatively large asset volatility. The study aims to help publishers make reasonable product design and pricing decisions

An Optimization Approach for pricing of Discrete European Call options Based on the Preference of Investors

Firstly, a method for measuring the risk aversion of investors was proposed based on the prospect theory. Secondly, under a sole hypothetical condition in which the risk aversion degree for different assets is the same in a market, the pricing of discrete European options was given based on the objective probability. Thirdly, it was proven that the European option price obtained was a non-arbitrate price. And then, both for the binomial tree, which is a complete market, and for the trinomial tree, which is an incomplete market, pricing European options were discussed by implementing the method provided in this paper. Lastly, an illustration is used to demonstrate how to estimate preference parameters from market data and how to calculate options prices. The result states that the method in this paper is the same as the traditional risk-neutral methods in a complete market, but it is different from the traditional risk-neutral methods in an incomplete market, and more, the price obtained in this paper is affected by the objective probability and also contains the risk attitude of the investors

Effects of Different Soccer Stud Configurations on Knee Kinematlcs and Shoe-Surface Traction of Sidestep Cutting Movement on Natural Grass

The purpose of this study was to inwstigate the effect of different stud configuration on knee joint kinematics of sidestep cutting movement on natural grass. A total of 14 amateur soccer players participated in the tests. Participants were asked to complete tasks of 45" sidestep cutting at the speed of 5.0M+-2m/s on natural grass. They selected soccer s h m with firm ground design (FG), artificial ground design (AG) and turf cleats (TF) randomly. During 45" cut, peak knee flexion (p less than 0.001) and abduction angles (

A LONGITUDINAL ANALYSIS OF CENTER OF PRESSURE IN PREGNANT GAIT THROUGHOUT PREGNANCY AND POST-PARTUM

The changes of physiological and morphological during pregnancy muld lead to gait pattern's changes. The aim of this study was to analysis the variation of pregnancy gait balance. Sixteen healthy pregnant women by choosing were performed during the second and third trimesters and again post-partum. Novel EMED was used for measuring the trajectory of the centre of pressure (COP). The results revealed that COP deviation distance (Dn) significantly increase in third trimester compared with post-partum during the initial contact phase (P=0.038). No differences were observed in the deviation distance of trimesters and postpartum during the forefoot push off phase. This method and results maybe have a new sight to reveal the dynamic stability with advanced pregnancy

BlOMECHANlCAL ANALYSIS OF VERTICAL JUMP WITH DIFFERENT FOREFOOT MORPHOLOGY

This study examined biomechanical differences between habitually barefoot male and habitually shod male during vertical jump. Foot morphology was measured with Easy-Foot-Scan. Foot kinetics and ankle kinematics were obtained from EMED pressure platform and Vicon motion analysis system as completing vertical jumps under barefoot condition. The results showed that habitually barefoot subjects had a significantly larger minimal distance between hallux and other toes. habitually unshod subjects showed larger loading under hallux and medial forefoot, while habitually shod subjects presented larger loading under medial and central forefoot. in addition, habitually barefoot male had smaller ankle plantarflexion, eversion and external rotation during vertical jump. Differences of kinematics and kinetics during vertical jump might attribute to the morphological differences in the toes region, which possibly explain the foot injury risks between habitually barefoot and habitually shod individuals

Stable solitary waves for a class of nonlinear Schrödinger system with quadratic interaction

We consider the existence and orbital stability of bound state solitary waves and ground state solitary waves for a class of nonlinear Schrödinger system with quadratic interaction in Rn (n = 2, 3). The existence of bound state and ground state solitary waves are studied by variational arguments and Concentration-compactness Lemma. In additional, we also prove the orbital stability of bound state and ground state solitary waves

Stable solitary waves for a class of nonlinear Schrödinger system with quadratic interaction

We consider the existence and orbital stability of bound state solitary waves and ground state solitary waves for a class of nonlinear Schrödinger system with quadratic interaction in $\mathbb{R}^n$ ($n=2,3$). The existence of bound state and ground state solitary waves are studied by variational arguments and Concentration-compactness Lemma. In additional, we also prove the orbital stability of bound state and ground state solitary waves