Search results for "Dynamic"
showing 10 items of 12329 documents
Network Dynamics of an Energy Supply Chain: Applicability of the Network Approach to Analysing the Industrial Ecology Practices of Companies
2006
Currently firms face environmental challenges, which require more emphasis on inter-organisational environmental improvement efforts. A field of study of industrial ecology offers some novel approaches for inter-organisational environmental management. It emphasises symbiotic linkages between firms or other organisations in which waste of one actor is used as raw material by others. The industrial network approach has been suggested as a possible framework for developing managerial implications for industrial ecology. This study analyses an example of an industrial ecosystem with notions of the network theory, and concludes that the industrial network approach is useful in analysing and des…
Dynamic Modeling of the Cyber Security Threat Problem
2009
This chapter discusses the possible growth of black markets (BMs) for software vulnerabilities and factors affecting their spread. It is difficult to collect statistics about BMs for vulnerabilities and their associated transactions, as they are hidden from general view. We conduct a disguised observation of online BM trading sites to identify causal models of the ongoing viability of BMs. Our observation results are expressed as a system dynamic model. We implement simulations to observe the effects of possible actions to disrupt BMs. The results suggest that without interventions the number and size of BMs is likely to increase. A simulation scenario with a policy to halt BM operations re…
Employing fuzzy logic in the diagnosis of a clinical case
2010
Fuzzy logic is a logical calculus which operates with many truth values (while classical logic works with the two values of true and false). Since fuzzy logic considers the truth of scientific statements like something softened, it is fruitfully applied to the study of biological phenomena, biology is indeed considered the field of complexity, uncertainty and vagueness. In this paper fuzzy logic is successfully applied to the clinical diagnosis of a patient who suffers from different diseases bound by a complex causal chain. In this work it is presented a mathematical foundation of fuzzy logic (with connectives and inference rules) and then the application of fuzzy reasoning to the study of…
Spatial dispersion intensity measure of phase concentration distributions and its applications to quantitative characterization, distinguishing and c…
2008
A method of evaluation of spatial dispersion of structures is presented. A quantitative parameter measuring spatial dispersion is introduced. It is shown that this parameter indeed measures spatial dispersion. A classification of bubble flow structures based on values of this parameter is proposed. An example of application of the method to real flow structures is presented.
Rigal — a programming language for compiler writing
2005
A new programming language for compiler writing is described. The main data structures are atoms, lists and trees. The control structures are based on advanced pattern matching. All phases of compilation, including parsing, optimization and code generation, can be programmed in this language in short and readable form. Sample compiler written in RIGAL is presented.
157 Patient satisfaction and safety of sedation using perineurial dexmedetomidine in axillary brachial plexus block for wrist surgery
2021
Background and Aims Dexmedetomidine is known to prolong the duration of regional block while its sedative effect when administered perineurally is unknown.[1] We aim to evaluate the effect of perineural Dexmedetomidine on the systemic sedation in patients after axillary brachial plexus block (ABPB). Methods This prospective randomized control trial includes 78 patients undergoing wrist surgery receiving ABPB. The study was conducted with the approval of Ethics Committee of Riga Stradins University. Patients were randomized into two groups – control (CG) (N=39) and study group (SG) (N=39). Both groups received ABPB with a standard dose of local anaesthetics. The study group also received 100…
Signal processing procedures for the evaluation of the cardiovascular effects in the obstructive sleep apnea syndrome
2002
A new index, the cross-power index (CPI), is proposed to quantify the severity of obstructive sleep apnea syndrome (OSAS) in terms of its cardiovascular effects. On the basis of the influences that recurring drops in oxygen saturation have on systolic blood pressure variability of OSAS patients, CPI is defined as the integral of the cross-spectrum modulus between systolic blood pressure and oxygen saturation. In a test group of 22 subjects, CPI correctly identified all 15 OSAS patients included in the pool. Moreover, evaluation of CPI in six OSAS patients sleeping with and without a CPAP (continuous positive airway pressure) device demonstrated that CPAP treatment substantially reduced the …
Large-eddy simulations of turbulent flow with heat transfer in simple and complex geometries using Harwell-FLOW3D
1996
Abstract Large-eddy simulation (LES) results are presented and discussed for the turbulent flow with heat transfer in different geometrical configurations, including a plane channel, a channel bearing transverse square ribs on one of the walls, and a crossed-corrugated air heater. They were obtained using the computational fluid dynamics (CFD) code Harwell-FLOW3D (Release 2), finite-volume grids having up to 423 nodes, and the Smagorinsky subgrid model with several variants regarding near-wall damping and wall boundary conditions. The first problem (plane turbulent Poiseuille flow with heat transfer) was mainly used as a benchmark to investigate the influence of numerical methods (pressure-…
Ventilation/perfusion ratios measured by multiple inert gas elimination during experimental cardiopulmonary resuscitation
2014
Background During cardiopulmonary resuscitation (CPR) the ventilation/perfusion distribution (VA/Q) within the lung is difficult to assess. This experimental study examines the capability of multiple inert gas elimination (MIGET) to determine VA/Q under CPR conditions in a pig model. Methods Twenty-one anaesthetised pigs were randomised to three fractions of inspired oxygen (1.0, 0.7 or 0.21). VA/Q by micropore membrane inlet mass spectrometry-derived MIGET was determined at baseline and during CPR following induction of ventricular fibrillation. Haemodynamics, blood gases, ventilation distribution by electrical impedance tomography and return of spontaneous circulation were assessed. Inter…
Low-Cost Sensor Based on SDR Platforms for TETRA Signals Monitoring
2021
The paper presents the design and implementation of an electromagnetic field monitoring sensor for the measurement of the Terrestrial Truncked Radio (TETRA) signals using low-cost software defined radio (SDR) platforms. The sensor includes: an SDR platform, a Global Positioning System (GPS) module and a hardware control module. Several SDR platforms having different resolutions of the analog–digital converters were tested in the first phase. The control module was implemented in two variants: a fixed one, using a laptop, and a mobile one, using a Raspberry Pi. The tests demonstrate the following achieved performances: instantaneous acquisition band of 5.12 MHz