Profit maximization in an inventory system with time-varying demand, partial backordering and discrete inventory cycle

In this paper, an inventory problem where the inventory cycle must be an integer multiple of a known basic period is considered. Furthermore, the demand rate in each basic period is a power time-dependent function. Shortages are allowed but, taking necessities or interests of the customers into account, only a fixed proportion of the demand during the stock-out period is satisfied with the arrival of the next replenishment. The costs related to the management of the inventory system are the ordering cost, the purchasing cost, the holding cost, the backordering cost and the lost sale cost. The problem is to determine the best inventory policy that maximizes the profit per unit time, which is the difference between the income obtained from the sales of the product and the sum of the previous costs. The modeling of the inventory problem leads to an integer nonlinear mathematical programming problem. To solve this problem, a new and efficient algorithm to calculate the optimal inventory cycle and the economic order quantity is proposed. Numerical examples are presented to illustrate how the algorithm works to determine the best inventory policies. A sensitivity analysis of the optimal policy with respect to some parameters of the inventory system is developed. Finally, conclusions and suggestions for future research lines are given.

Asymmetry of muscle strength values during the basic period of rehabilitation after anterior cruciate ligament reconstruction in athletes

Objective: to specify the features of muscle strength imbalance values as the criteria defining intensity and progress of rehabilitation after anterior cruciate ligament (ACL) reconstruction in athletes. The study involved 46 athletes having ACL injury. All the injured were young people under 44 years of age according to the current WHO classification. The control group, or experimental group consisted of 23 patients, and there were 25 patient s in the main one. Physical rehabilitation program for the patients of the CG and MG included therapeutic exercises, massage, and electrical myostimulation. Physical rehabilitation program for the MG patients was aimed at the priority recovery of tone, strength and mass of hamstrings. The article evaluates the effect of the developed physical rehabilitation program on the relation of strength values of the injured and intact limbs during the basic period of rehabilitation. The CG patients showed positive changes only according to EMG (asymmetry index of the mean amplitude of the rectus femoris and vastus medialis (р <0,05), and the MG patients significantly restored the balance between muscle strength values according to dynamometry results (moment of hip flexors and extensors strength, р<0,01; asymmetry index of hip flexors and extensors strength, р<0,05), and EMG (asymmetry index of the mean amplitude of the rectus femoris and vastus medialis, р<0,05). The study found that physical therapy program which additionally included electrical myostimulation and special exercises for hamstrings has significant effect on the relation of strength values of the injured and intact limbs during the basic period of rehabilitation.

A review on psycho physiological impacts of yoga on Anxiety in undergraduate students

Undergraduate students are defenseless against a basic period in formative development, confronting thorough scholastic work, and figuring out how to work autonomously. Physical exercises, for example, running and bicycling have been appeared to improve temperament and alleviate pressure. In any case, understudies regularly have low degrees of physical movement. Yoga is an antiquated physical and mental movement that influences temperament and anxiety. Be that as it may, considers looking at the psycho physiological impacts of yoga are uncommon in peer-checked on diaries. The point of this examination is to build up fundamental proof for the psycho physiological impacts of yoga on worry in youthful grown-up understudies. The current investigation proposes that yoga effect sly affects a psycho physiological level that prompts diminished degrees of worry in undergrad. Further research is expected to look at the degree to which various kinds of yogic practices address the necessities of various school subpopulations.

Modeling of sunflower’s productivity under future climate changes in Ukraine considering the scenarios of RCP anthropogenic impact

Climate change is one of the major global issues. Climate is one of the most significant factors determining the level of crop yields, including sunflower crops. Currently the sunflower planting acreage in Ukraine has already reached its maximum value. Therefore the potential for increasing sunflower production should be aimed at increasing its yield. To assess the impact of climate change on sunflower productivity the article considers modern scenarios of RCP (Representative Concentration Pathways) such as RCP 4.5 and RCP 8.5. They belong to the scenarios of medium and high levels of greenhouse gas emissions. The RCP 4.5 and RCP 8.5 scenarios cover the climatic period from 2021 to 2050. In order to conduct a comparative analysis of scenario meteorological values with previous data from the Agroclimatic Reference Book of Ukraine, the period from 1986 to 2005 was taken. It serves as a basic period for calculations. Calculations were made for the following natural and climatic zones of Ukraine: East Forest-Steppe, Northern and Southern Steppe. The article studies the influence of agroclimatic conditions on sunflower cultivation as per two interphase periods: shoots - blooming and blooming - picking maturity. Study of sunflower productivity formation was carried out using a mathematical model of the water-heat regime and sunflower productivity. The model is based on the system of equations of radiation, heat and water balances and biomass balance in vegetation cover. According to calculations a lowered temperature regime and sufficient moisture in the first half of sunflower vegetation season will favor the formation of leaves way more than during the basic period within the entire area under study. However, expected arid conditions in the second half of vegetation period will cause a very low sunflower moisture availability during this period which would lead to reduction of sunflower seeds' crop-producing power. Analysis of agroclimatic conditions during vegetation season from sunflower shoots to its picking maturity showed that implementation of both scenarios would ensure expected weather conditions to be more favorable for sunflower growing in the eastern forest-steppe zone of Ukraine. The greatest risk of sunflower crops shortfall in certain years is expected in the southern steppe zone of Ukraine and significant losses should be expected in case of scenario RCP4.5 implementation.