Investigation and performance optimization of mesh networking in Zigbee

The aim of this research paper is to perform a detailed investigation and performance optimization of mesh networking in Zigbee. ZigBee applications are open and global wireless technology that are based on IEEE 802.15.4 standard, it is used for sense and control in many fields like, military, commercial, industrial and medical applications. Extending ZigBee lifetime is a high demand in many ZigBee networks industry and applications, and since the lifetime of ZigBee nodes depends mainly on batteries for their power, the desire for developing a scheme or methodology that support power management and saving battery lifetime is of a great requirement. In this research work, a power sensitive routing Algorithm is proposed Power Sensitive Ad hoc On-Demand (PS-AODV) to develop protocol scheme and methodology of existing on-demand routing protocols, by introducing an algorithm that manages ZigBee operations and construct the route from trusted active nodes. Furthermore, many aspects of routing protocol in ZigBee mesh networks have been researched to concentrate on route discovery, route maintenance, neighbouring table, and shortest paths. PS-AODV routing algorithm is used in two different ZigBee mesh networks, with two different coordinator locations, one used at the centre and the other one at the corner of the networks. The extracted results conclude a better network operation for the coordinator located at the centre with an increase in the network lifetime around 20% percentage, and saved about 32.7% of delay time compare to AODV

On the issue of predictors of complications of surgical treatment of patients with spinal cord injury in the lower thoracic and lumbar spine

Objective. To determine the predictors of complications of surgical treatment of patients with spinal cord injury (SCI) in the lower thoracic and lumbar spine using various options for performing decompression and stabilization surgeries. Material and Methods. A total of 240 patients with spinal cord injury in the lower thoracic and lumbar spine were operated on in 2010–2021. All patients were divided into 3 groups depending on the tactical option of surgical treatment performed. In Group 1, patients (n = 129) underwent two-stage surgical intervention through combined approach: the first stage included transpedicular fixation (TPF) supplemented with posterior decompression options and the second stage – fusion through anterior approach, in Group 2 (n = 36) – TPF and decompression through posterior approach, and in Group 3 (n = 75) – one-stage surgical intervention including TPF, decompression and fusion through extended posterior approach. An analysis of surgical complications was carried out, and factors that increase the likelihood of their development were identified. Comparison of groups according to quantitative indicators was carried out using single-factor analysis of variance (with normal distribution), and Kruskal-Wallis test (with distribution other than normal). Comparison of percentages in the analysis of multifield contingency tables was performed using Pearson’s χ2 test. Results. A total of 130 cases of postoperative complications were identified that corresponded to the grade 2 or 3 of the Clavien – Dindo classification, including respiratory, infectious processes in the surgical site, iatrogenic neurological complications, intraoperative damage to the dura mater, and instability of metal fixation. In two-stage surgery through combined approaches, the most common were respiratory complications (17.1 %), intraoperative damage to the dura mater (9.3 %) and surgical site infection (7.0 %). Predictors of these complications included the severity of preoperative neurological deficit of ASIA grade A or B, the patient’s preoperative condition corresponding to the average risk of death according to the modified SOFA score, and the performance of extended laminectomy. In isolated TPF with reposition and stabilization without fusion, the most common complication was instability of metal fixation in the long-term period (47.1 %), the predictors of which were incomplete reposition of the fractured vertebral body and performing two-segment TPF. In one-stage decompression and stabilization interventions with TPF and fusion through the extended posterior approach, the most common complications were intraoperative damage to the dura mater (26.7 %), respiratory complications (18.7 %), infectious processes in the surgical site (10.7 %), iatrogenic neurological complications (12.0 %), and instability of metal fixation (16.1 %). Predictors of these complications were the severity of the patient’s condition before surgery, corresponding to the average risk of death according to the modified SOFA score, neurological deficit of type D or rapidly regressing neurological deficit of type C, A or B according to ASIA scale, and bisegmental fusion when the injury was located at the lumbar level. Conclusion. Analysis of the causes of complication development contributes to their prevention, and can also form the basis for algorithms to choose tactics and technology for performing decompression and stabilization operations

Implementation of the EU environmental law in the context of cross-border damage to marine environment: case study of the Baltic Sea

The purpose of the thesis is to analyse the applicability and implementation of the European Union (EU) environmental law to cross-border damage to the marine environment, also assessing their applicability to the Baltic Sea as well as progress on implementation, and additionally to review the relationship between the EU law and HELCOM – intergovernmental body responsible for carrying out the obligations under the Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea

Landfill Futures: : National Guideline Document

This report looks at the past and present roles of landfills in Australian waste management and considers the requirements for a sustainable future. The research used a test case to apply an integrated resource planning model to waste. The results suggest that disposal to landfill may be an expensive and less preferred option compared to others, in many cases, but still have a role to play in specific contexts where the costs of other options are higher

Coexistence of Competing Microbial Strains under Twofold Environmental Variability and Demographic Fluctuations

Microbial populations generally evolve in volatile environments, under conditions fluctuating between harsh and mild, e.g. as the result of sudden changes in toxin concentration or nutrient abundance. Environmental variability (EV) thus shapes the long-time population dynamics, notably by influencing the ability of different strains of microorganisms to coexist. Inspired by the evolution of antimicrobial resistance, we study the dynamics of a community consisting of two competing strains subject to twofold EV. The level of toxin varies in time, favouring the growth of one strain under low drug concentration and the other strain when the toxin level is high. We also model time-changing resource abundance by a randomly switching carrying capacity that drives the fluctuating size of the community. While one strain dominates in a static environment, we show that species coexistence is possible in the presence of EV. By computational and analytical means, we determine the environmental conditions under which long-lived coexistence is possible and when it is almost certain. Notably, we study the circumstances under which environmental and demographic fluctuations promote, or hinder, the strains coexistence. We also determine how the make-up of the coexistence phase and the average abundance of each strain depend on the EV

Robust Iterative Learning Control for Pneumatic Muscle with State Constraint and Model Uncertainty

In this paper, we propose a novel iterative learning control (ILC) scheme for precise state tracking of pneumatic muscle (PM) actuators. Two critical issues are considered in our scheme: 1) state constraints on PM position and velocity; 2) uncertainties of the PM model. Based on the three-element form, a PM model is constructed that takes both parametric and nonparametric uncertainties into consideration. By introducing the composite energy function (CEF) approach incorporated with a barrier Lyapunov function (BLF), full state constraints of PM will not be violated and uncertainties are effectively compensated. Through rigorous analysis, we show that under proposed ILC scheme, uniform convergence of PM state tracking errors are guaranteed. Simulation results validate the performance of the proposed scheme