The marked reduction of the Indus river flow downstream from the Kotry barrage: can the mangrove ecosystems of Pakistan survive in the resulting hypersaline environment?

This report deals with the application of knowledge of mangrove ecosystems from around the world to the understanding of the present status of mangroves ecosystems in Pakistan.

Evaluation of wave drag reduction by flow control

An analytical expression is proposed to estimate the wave drag of an aerofoil equipped with shock control. The analysis extends the conventional approach for a single normal shock wave, based on the knowledge that all types of successful shock control on transonic aerofoils cause bifurcated λ-shock structures. The influence of surface curvature on the λ-shock structure has been taken into account. The extended method has been found to produce fairly good agreement with the results obtained by CFD methods while requiring negligible computational effort. This new formulation is expected to be beneficial in the industrial design process of transonic aerofoils and wings where a large number of computational simulations have to be performed.

Rain igestion in axial flow compressors at part speed

New experimental work is reported on the effects of water ingestion on the performance of an axial flow compressor. The background to the work is the effect that heavy rain has on an aeroengine compressor when operating in a "descent idle" mode, i.e., when the compressor is operating at part speed and when the aeromechanical effects of water ingestion are more important than the thermodynamic effects. Most of our existing knowledge in this field comes from whole engine tests. The current work provides the first known results from direct measurements on a stand-alone compressor. The influence of droplet size on path trajectory is considered both computationally and experimentally to show that most rain droplets will collide with the first row of rotor blades. The water on the blades is then centrifuged toward the casing where the normal airflow patterns in the vicinity of the rotor tips are disrupted. The result of this disruption is a reduction in compressor delivery pressure and an increase in the torque required to keep the compressor speed constant. Both effects reduce the efficiency of the machine. The behavior of the water in the blade rows is examined in detail, and simple models are proposed to explain the loss of pressure rise and the increase in torque. The measurements were obtained in a low speed compressor, making it possible to study the mechanical (increase in torque) and aerodynamic (reduction in pressure rise) effects of water ingestion without the added complication of thermodynamic effects. Copyright © 2008 by ASME.

FLOW-PIPE-SEEPAGE COUPLING ANALYSIS OF SPANNING INITIATION OF A PARTIALLY-EMBEDDED PIPELINE

The initiation of pipeline spanning involves the coupling between the flow over the pipeline and the seepage-flow in the soil underneath the pipeline. The pipeline spanning initiation is experimentally observed and discussed in this article. It is qualitatively indicated that the pressure-drop induced soil seepage failure is the predominant cause for pipeline spanning initiation. A flow-pipe-seepage sequential coupling Finite Element Method (FEM) model is proposed to simulate the coupling between the water flow-field and the soil seepage-field. A critical hydraulic gradient is obtained for oblique seepage failure of the sand in the direction tangent to the pipe. Parametric study is performed to investigate the effects of inflow velocity, pipe embedment on the pressure-drop, and the effects of soil internal friction angle and pipe embedment-to-diameter ratio on the critical flow velocity for pipeline spanning initiation. It is indicated that the dimensionless critical flow velocity changes approximately linearly with the soil internal friction angle for the submarine pipeline partially-embedded in a sandy seabed.

Computational inference of neural information flow networks.

Determining how information flows along anatomical brain pathways is a fundamental requirement for understanding how animals perceive their environments, learn, and behave. Attempts to reveal such neural information flow have been made using linear computational methods, but neural interactions are known to be nonlinear. Here, we demonstrate that a dynamic Bayesian network (DBN) inference algorithm we originally developed to infer nonlinear transcriptional regulatory networks from gene expression data collected with microarrays is also successful at inferring nonlinear neural information flow networks from electrophysiology data collected with microelectrode arrays. The inferred networks we recover from the songbird auditory pathway are correctly restricted to a subset of known anatomical paths, are consistent with timing of the system, and reveal both the importance of reciprocal feedback in auditory processing and greater information flow to higher-order auditory areas when birds hear natural as opposed to synthetic sounds. A linear method applied to the same data incorrectly produces networks with information flow to non-neural tissue and over paths known not to exist. To our knowledge, this study represents the first biologically validated demonstration of an algorithm to successfully infer neural information flow networks.

Host-based P2P flow identification and use in real-time

Data identification is a key task for any Internet Service Provider (ISP) or network administrator. As port fluctuation and encryption become more common in P2P traffic wishing to avoid identification, new strategies must be developed to detect and classify such flows. This paper introduces a new method of separating P2P and standard web traffic that can be applied as part of a data mining process, based on the activity of the hosts on the network. Unlike other research, our method is aimed at classifying individual flows rather than just identifying P2P hosts or ports. Heuristics are analysed and a classification system proposed. The accuracy of the system is then tested using real network traffic from a core internet router showing over 99% accuracy in some cases. We expand on this proposed strategy to investigate its application to real-time, early classification problems. New proposals are made and the results of real-time experiments compared to those obtained in the data mining research. To the best of our knowledge this is the first research to use host based flow identification to determine a flows application within the early stages of the connection.

The determinants of knowledge transfer within collaborative new product development projects

Purpose – This paper explores the factors which determine the degree of knowledge transfer in inter-firm new product development projects. We test a theoretical model exploring how inter-firm knowledge transfer is enabled or hindered by a buyer’s learning intent, the degree of supplier protectiveness, inter-firm knowledge ambiguity, and absorptive capacity. Design/methodology/approach – A sample of 153 R&D intensive manufacturing firms in the UK automotive, aerospace, pharmaceutical, electrical, chemical, and general manufacturing industries were used to test the framework. Two-step structural equation modeling in AMOS 7.0 was used to analyse the data. Findings – Our results indicate that a buyer’s learning intent increases inter-firm knowledge transfer, but also acts as an incentive for suppliers to protect their knowledge. Such defensive measures increase the degree of inter-firm knowledge ambiguity, encouraging buyer firms to invest in absorptive capacity as a means to interpret supplier knowledge, but also increase the degree of knowledge transfer. Practical implications – Our paper illustrates the effects of focusing on acquisition, rather than accessing, supplier technological knowledge. We show that an overt learning strategy can be detrimental to knowledge transfer between buyer-supplier, as supplier’s react by restricting the flow of information. Organisations are encouraged to consider this dynamic when engaging in multi-organisational new product development projects. Originality/value – This paper examines the dynamics of knowledge transfer within inter-firm NPD projects, showing how transfer is influenced by the buyer firm’s learning intention, supplier’s response, characteristics of the relationship and knowledge to be transferred.

Microwave-assisted Cu-catalyzed Ullmann ether synthesis in a continuous-flow milli-plant

The combination of milli-scale processing and microwave heating has been investigated for the Cu-catalyzed Ullmann etherification in fine-chemical synthesis, providing improved catalytic activity and selective catalyst heating. Wall-coated and fixed-bed milli-reactors were designed and applied in the Cu-catalyzed Ullmann-type CO coupling of phenol and 4-chloropyridine. In a batch reactor the results show clearly increased yields for the microwave heated process at low microwave powers, whereas high powers and catalyst loadings reduced the benefits of microwave heating. Slightly higher yields were found in the Cu/ZnO wall-coated as compared to the Cu/TiO fixed-bed flow-reactor. The benefit here is that the reaction occurs at the surface of the metal nanoparticles confined within a support film making the nano-copper equally accessible. Catalyst deactivation was mainly caused by Cu oxidation and coke formation; however, at longer process times leaching played a significant role. Catalyst activity could partially be recovered by removal of deposited by-product by means of calcination. After 6h on-stream the reactor productivities were 28.3 and 55.1kgprod/(mR3h) for the fresh Cu/ZnO wall-coated and Cu/TiO fixed-bed reactor, respectively. Comparison of single- and multimode microwaves showed a threefold yield increase for single-mode microwaves. Control of nanoparticles size and loading allows to avoid high temperatures in a single-mode microwave field and provides a novel solution to a major problem for combining metal catalysis and microwave heating. Catalyst stability appeared to be more important and provided twofold yield increase for the CuZn/TiO catalyst as compared to the Cu/TiO catalyst due to stabilized copper by preferential oxidation of the zinc. For this catalyst a threefold yield increase was observed in single-mode microwaves which, to the best of our knowledge, led to a not yet reported productivity of 172kgprod/(mR3h) for the microwave and flow Ullmann CO coupling. © 2012 Elsevier B.V.

Sliding window two-thermocouple sensor characterization for variable flow environments

A two-thermocouple sensor characterization method for use in variable flow applications is proposed. Previous offline methods for constant velocity flow are extended using sliding data windows and polynomials to accommodate variable velocity. Analysis of Monte-Carlo simulation studies confirms that the unbiased and consistent parameter estimator outperforms alternatives in the literature and has the added advantage of not requiring a priori knowledge of the time constant ratio of thermocouples. Experimental results from a test rig are also presented. © 2008 The Institute of Measurement and Control.

Threats and knowledge gaps for ecosystem services provided by kelp forests: a northeast Atlantic perspective.

Kelp forests along temperate and polar coastlines represent some of most diverse and productive habitats on the Earth. Here, we synthesize information from >60 years of research on the structure and functioning of kelp forest habitats in European waters, with particular emphasis on the coasts of UK and Ireland, which represents an important biogeographic transition zone that is subjected to multiple threats and stressors. We collated existing data on kelp distribution and abundance and reanalyzed these data to describe the structure of kelp forests along a spatial gradient spanning more than 10° of latitude. We then examined ecological goods and services provided by kelp forests, including elevated secondary production, nutrient cycling, energy capture and flow, coastal defense, direct applications, and biodiversity repositories, before discussing current and future threats posed to kelp forests and identifying key knowledge gaps. Recent evidence unequivocally demonstrates that the structure of kelp forests in the NE Atlantic is changing in response to climate- and non-climate-related stressors, which will have major implications for the structure and functioning of coastal ecosystems. However, kelp-dominated habitats along much of the NE Atlantic coastline have been chronically understudied over recent decades in comparison with other regions such as Australasia and North America. The paucity of field-based research currently impedes our ability to conserve and manage these important ecosystems. Targeted observational and experimental research conducted over large spatial and temporal scales is urgently needed to address these knowledge gaps.

Testing Tidal Turbines Part II: Tidal Flow Characterisation Using ADV Data

The study outlined in Testing Tidal Turbines Part 1 explains the variation in performance between turbines operating in steady and turbulent flow conditions. However, the impact of turbulence on devices is generally not well understood. Furthermore, the turbulence characteristics of high velocity marine currents have not been extensively studied. Therefore, knowledge of their characteristics must be expanded and methodologies to predict the impact of the characteristics on devices developed and improved. This study examines the measurement of tidal currents at a site used for testing of medium scale tidal turbines. The data being discussed was collected with a point velocimeter (ADV). The processing procedures implemented are discussed and the resulting estimated turbulence spectra and turbulence intensities are presented. The results contribute to the improvement of knowledge regarding tidal current characteristics. This will be fundamental to the optimisation of the design and operation of tidal stream devices.

Analysis of a three-dimensional flow generated by a linear aerospike

Linear aerospike nozzles are envisaged as a possible means to improve launcher engine performance. One of the most interesting properties of these nozzles is the possibility of a good integration with the vehicle. To improve the knowledge of the flow-field and performance of aerospike nozzles, they are studied numerically, with particular attention to the differences between the basic two-dimensional nozzle, usually considered in the design phase, and the more realistic three-dimensional nozzle. The study considers also the effect of flight condition, which cannot be neglected because of the characteristic external expansion of aerospike nozzles.

Molecular dynamics simulation investigation on the plastic flow behaviour of silicon during nanometric cutting

Molecular dynamics (MD) simulation was carried out to acquire an in-depth understanding of the flow behaviour of single crystal silicon during nanometric cutting on three principal crystallographic planes and at different cutting temperatures. The key findings were that (i) the substrate material underneath the cutting tool was observed for the first time to experience a rotational flow akin to fluids at all the tested temperatures up to 1200 K. (ii) The degree of flow in terms of vorticity was found higher on the (1 1 1) crystal plane signifying better machinability on this orientation in accord with the current pool of knowledge (iii) an increase in the machining temperature reduces the springback effect and thereby the elastic recovery and (iv) the cutting orientation and the cutting temperature showed significant dependence on the location of the stagnation region in the cutting zone of the substrate.

Preoperative radial artery volume flow is predictive of arteriovenous fistula outcomes

Objective: Guidelines recommend the creation of a wrist radiocephalic arteriovenous fistula (RAVF) as initial hemodialysis vascular access. This study explored the potential of preoperative ultrasound vessel measurements to predict AVF failure to mature (FTM) in a cohort of patients with end-stage renal disease in Northern Ireland

.Methods: A retrospective analysis was performed of all patients who had preoperative ultrasound mapping of upper limb blood vessels carried out from August 2011 to December 2014 and whose AVF reached a functional outcome by March 2015.

Results: There were 152 patients (97% white) who had ultrasound mapping andan AVF functional outcome recorded; 80 (54%) had an upper arm AVF created, and 69 (46%) had a RAVF formed. Logistic regression revealed that female gender (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.12-5.55; P = .025), minimum venous diameter (OR, 0.6; 95% CI, 0.39-0.95; P = .029), and RAVF (OR, 0.4; 95% CI, 0.18-0.89; P = .026) were associated with FTM. On subgroup analysis of the RAVF group, RAVFs with an arterial volume flow <50 mL/min were seven times as likely to fail as RAVFs with higher volume flows (OR, 7.0; 95% CI, 2.35-20.87; P < .001).

Conclusions: In this cohort, a radial artery flow rate <50 mL/min was associated with a sevenfold increased risk of FTM in RAVF, which to our knowledge has not been previously reported in the literature. Preoperative ultrasound mapping adds objective assessment in the clinical prediction of AVF FTM.

Bridging Knowledge Gaps in the Management of Acute Coronary Syndromes

Contexte L’occlusion d’une artère du cœur cause un syndrome coronarien aigu (SCA) soit avec une élévation du segment ST (IAMEST) ou sans élévation du segment ST (1). Le traitement des patients avec un IAMEST requiert soit une intervention coronarienne d’urgence (ICP primaire) ou une thérapie fibrinolytique (FL). La thérapie FL peut être administrée soit dans un contexte pré-hospitalier (PHL) ou à l’hôpital. Une prise en charge précoce des patients avec SCA peut être améliorée par un simple indice de risque. Objectifs Les objectifs de cette thèse étaient de : 1) comparer l’ICP primaire et la thérapie FL (2); décrire plusieurs systèmes internationaux de PHL; (3) développer et valider un indice de risque simplifié pour une stratification précoce des patients avec SCA. Méthodes Nous complétons des méta-analyses, de type hiérarchique Bayésiennes portant sur l’effet de la randomisation, d’études randomisées et observationnelles; complétons également un sondage sur des systèmes internationaux de PHL; développons et validons un nouvel indice de risque pour ACS (le C-ACS). Résultats Dans les études observationnelles, l’ICP primaire, comparée à la thérapie FL, est associée à une plus grande réduction de la mortalité à court-terme; mais ce sans bénéfices concluants à long terme. La FL pré-hospitalière peut être administrée par des professionnels de la santé possédant diverses expertises. Le C-ACS a des bonnes propriétés discriminatoires et pourrait être utilisé dans la stratification des patients avec SCA. Conclusion Nous avons comblé plusieurs lacunes importantes au niveau de la connaissance actuelle. Cette thèse de doctorat contribuera à améliorer l’accès à des soins de qualité élevée pour les patients ayant un SCA.