Streaming Rate Research Articles

Concentrating of Sugar Syrup in Bioethanol Production Using Sweeping Gas Membrane Distillation.

Membrane distillation (MD) is a relatively new and underdeveloped separation process which can be classified as a green technology. However, in order to investigate its dark points, sensitivity analysis and optimization studies are critical. In this work, a number of MD experiments were performed for concentrating glucose syrup using a sweeping gas membrane distillation (SGMD) process as a critical step in bioethanol production. The experimental design method was the Taguchi orthogonal array (an L9 orthogonal one) methodology. The experimental results showed the effects of various operating variables, including temperature (45, 55, and 65 °C), flow rate (200, 400, and 600 ml/min) and glucose concentration (10, 30, and 50 g/l) of the feed stream, as well as sweeping gas flow rate (4, 10, and 16 standard cubic feet per hour (SCFH)) on the permeate flux. The main effects of the operating variables were reported. An ANOVA analysis showed that the most and the least influenced variables were feed temperature and feed flow rate, each one with 62.1% and 6.1% contributions, respectively. The glucose rejection was measured at 99% for all experiments. Results indicated that the SGMD process could be considered as a versatile and clean process in the sugar concentration step of the bioethanol production.

Multiplexing Zero-Error and Rare-Error Communications Over a Noisy Channel

Two independent data streams are to be transmitted over a noisy discrete memoryless channel with noiseless (ideal) feedback. Errors are tolerated only in the second stream, provided that they occur with vanishing probability. The rate of the error-free stream cannot, of course, exceed the channel's zero-error feedback capacity, and nor can the sum of the streams' rates exceed the channel's Shannon capacity. Using a suitable coding scheme, these necessary conditions are shown to characterize all the achievable rate pairs. Planning for the worst channel behavior-as is needed to achieve zero-error communication-and planning for the typical channel behavior-as is needed to communicate near the Shannon limit-are thus not incompatible. It is further shown that feedback may be beneficial for the multiplexing problem even on channels on which it does not increase the zero-error capacity.

Chip-based sensing for release of unprocessed cell surface proteins in vitro and in serum and its (patho)physiological relevance.

To study the possibility that certain components of eukaryotic plasma membranes are released under certain (patho)physiological conditions, a chip-based sensor was developed for the detection of cell surface proteins, which are anchored at the outer leaflet of eukaryotic plasma membranes by a covalently attached glycolipid, exclusively, and might be prone to spontaneous or regulated release on the basis of their amphiphilic character. For this, unprocessed, full-length glycosylphosphatidylinositol-anchored proteins (GPI-AP), together with associated phospholipids, were specifically captured and detected by a chip- and microfluidic channel-based sensor, leading to changes in phase and amplitude of surface acoustic waves (SAW) propagating over the chip surface. Unprocessed GPI-AP in complex with lipids were found to be released from rat adipocyte plasma membranes immobilized on the chip, which was dependent on the flow rate and composition of the buffer stream. The complexes were identified in the incubation medium of primary rat adipocytes, in correlation to the cell size, and in rat as well as human serum. With rats, the measured changes in SAW phase shift, reflecting specific mass/size or amount of the unprocessed GPI-AP in complex with lipids, and SAW amplitude, reflecting their viscoelasticity, enabled the differentiation between the lean and obese (high-fat diet) state, and the normal (Wistar) and hyperinsulinemic (Zucker fatty) as well as hyperinsulinemic hyperglycemic (Zucker diabetic fatty) state. Thus chip-based sensing for complexes of unprocessed GPI-AP and lipids reveals the inherently labile anchorage of GPI-AP at plasma membranes and their susceptibility for release in response to (intrinsic/extrinsic) cues of metabolic relevance and may, therefore, be useful for monitoring of (pre-)diabetic disease states.

On Achieving the Maximum Streaming Rate in Hybrid Wired/Wireless Overlay Networks

In this letter, we study the multicast streaming problem in a fully connected hybrid wired/wireless overlay. We derive explicit formulas for the maximum streaming rate and the hybrid multiplicity using a flow-based method. The considered model supports both full-duplex and half-duplex modes, and incorporates equal service and differentiated service in a unified framework. The obtained results have theoretical and practical significance in wired/wireless content distribution.

Techno-Economic Assessment of a Scaled-Up Meat Waste Biorefinery System: A Simulation Study.

While exports from the meat industry in New Zealand constitute a valuable source of foreign exchange, the meat industry is also responsible for the generation of large masses of waste streams. These meat processing waste streams are largely biologically unstable and are capable of leading to unfavourable environmental outcomes if not properly managed. To enable the effective management of the meat processing waste streams, a value-recovery based strategy, for the complete valorisation of the meat processing waste biomass, is proposed. In the present study therefore, a biorefinery system that integrates the biomass conversion technologies of hydrolysis, esterification, anaerobic digestion and hydrothermal liquefaction has been modelled, simulated and optimized for enhanced environmental performance and economic performance. It was determined that an initial positive correlation between the mass feed rate of the waste to the biorefinery system and its environmental performance exists. However, beyond an optimal total mass feed rate of the waste stream there is a deterioration of the environmental performance of the biorefinery system. It was also determined that economies of scale ensure that any improvement in the economic performance of the biorefinery system with increasing total mass feed rate of the waste stream, is sustained. The present study established that the optimized meat waste biorefinery system facilitated a reduction in the unit production costs of the value-added products of biodiesel, biochar and biocrude compared the literature-obtained unit production costs of the respective aforementioned products when generated from stand-alone systems. The unit production cost of biogas was however shown to be comparable to the literature-obtained unit production cost of biogas. Finally, the present study showed that the optimized meat processing waste biorefinery could achieve enhanced economic performance while simultaneously maintaining favourable environmental sustainability.

О СКОРОСТИ СОВМЕСТНОГО ГОРЕНИЯ СТРУИ И ЛУЖИ ЖИДКОГО НАТРИЯ

Sodium fires with heat and fume release often happen at coolant circuit rupture of sodium fast reactor. At nuclear power plant with the sodium fast reactor the more probable scenario of sodium fire is considered burning of falling from damaged pipeline liquid sodium stream and the pool formed under it. The simple models for sodium fire which contains minimum of phenomenological parameters and gives the opportunity to get the upper limits of heat generation and amount of aerosol generated at sodium fire are more preferable. The physical and mathematical model for estimation a combined burning rate of the freely falling liquid sodium stream and the pool formed under it is proposed. The model is based on the laws of energy and mass conservation, the empiric correlations for burning rate of stream and pool sodium and assumption that pool depth cannot be less than equilibrium. The equilibrium pool depth depends on surface tension of liquid sodium. The probable heat transfer techniques for steam-phase and heterogeneous burning of metal are discussed. The experimental data of the Monju's sodium fire imitation are used for verification of the model presented. Good agreement between experimental and calculated data is observed.

State and runtime-aware scheduling in elastic stream computing systems

State and runtime-aware scheduling is one of the problems that is hard to resolve in elastic big data stream computing systems, as the state of each vertex is different, and the arrival rate of data streams fluctuates over time. A state and runtime-aware scheduling framework should be able to dynamically adapt to the fluctuation of the arrival rate of data streams and be aware of vertex states and resource availability. Currently, there is an increasing number of research work focusing on application scheduling in stream computing systems, however, this problem is still far from being completely solved. In this paper, we focus on the state of vertex in applications and the runtime feature of resources in a data center, and propose a state and runtime-aware scheduling framework (Sra-Stream) for elastic streaming computing systems, which incorporates the following features: (1) Profiling mathematical relationships between the system response time and the arrival rate of data streams, and identifying relevant resource constraints to meet the low response time and high throughput objectives. (2) Classifying vertex into stateless vertex or stateful vertex from a quantitative perspective, and achieving vertex parallelization by considering the state of the vertex. (3) Demonstrating a proposed stream application scheduling scheme consisting of a modified first-fit based runtime-aware data tuple scheduling strategy at the initial stage, and a maximum latency-sensitive based runtime-aware data stream scheduling strategy at the online stage, by considering the current scheduling status of the application. (4) Evaluating the achievement levels of low response time and high throughput objectives in a real-world elastic stream computing system. Experimental results conclusively demonstrate that the proposed Sra-Stream provides significant performance improvements on achieving the low system response time and high system throughput.

Stochastic Optimization From Distributed Streaming Data in Rate-Limited Networks

Motivated by machine learning applications in networks of sensors, internet-of-things (IoT) devices, and autonomous agents, we propose techniques for distributed stochastic convex learning from high-rate data streams. The setup involves a network of nodes---each one of which has a stream of data arriving at a constant rate---that solve a stochastic convex optimization problem by collaborating with each other over rate-limited communication links. To this end, we present and analyze two algorithms---termed distributed stochastic approximation mirror descent (D-SAMD) and accelerated distributed stochastic approximation mirror descent (AD-SAMD)---that are based on two stochastic variants of mirror descent and in which nodes collaborate via approximate averaging of the local, noisy subgradients using distributed consensus. Our main contributions are (i) bounds on the convergence rates of D-SAMD and AD-SAMD in terms of the number of nodes, network topology, and ratio of the data streaming and communication rates, and (ii) sufficient conditions for order-optimum convergence of these algorithms. In particular, we show that for sufficiently well-connected networks, distributed learning schemes can obtain order-optimum convergence even if the communications rate is small. Further we find that the use of accelerated methods significantly enlarges the regime in which order-optimum convergence is achieved; this is in contrast to the centralized setting, where accelerated methods usually offer only a modest improvement. Finally, we demonstrate the effectiveness of the proposed algorithms using numerical experiments.

Sorption of Hydrogen Chloridein The Fluidized Bed Reactor

Abstract Combustion of fuels, including renewable fuels and thermal treatment of waste (CFCs, pesticides), is associated with emissions of pollutants including halogens. The reversible process of sorption/desorption of HCl, in a fluidized (bubbling) bed reactor (BFB), during co-combustion of Cl-materials, was carried out. The thermal decomposition of methylene chloride (DCM, CH2Cl2) in an inert sand bed with the addition of the hydroxyapatite sorbent (HAp, Ca5(PO4)3(OH)) was investigated. The process parameters were as follows: temperature - 930 °C, the air excess - 1.3, stream rate of CH2Cl2 - 50 cm3/h. The concentration of HCl, CCl4, CHCl3, CH2Cl2, CH3Cl, COCl2 in the exhaust gases were monitored online with FTIR spectroscopy. The main chlorine product was hydrogen chloride. Samples of unprocessed HAp, taken from the bed during the process, and solid apatite residues were analyzed by X-ray diffraction (XRD). The content of chlorapatite (Ca5(PO4)3Cl) in the analyzed samples was respectively 11, 53 and 19 %. X-ray fluorescence (XRF) analysis showed the molar ratio of Ca:P:Cl was: 1.00:0.36:0.01, 1.00:0.36:0.09, 1.00:0.37:0.04 respectively. The HAp could be used as an sorbent of the HCl(g) during combustion of materials containing chlorine.

Multifunctional microchip-based distillation apparatus I - Steam distillation for formaldehyde detection

A multifunctional microchip-based distillation apparatus for distilling and detecting formaldehyde (CH2O) in food products is developed. The presented apparatus comprises a disposable microchip, a steam supply system, and a recirculating cooling water supply. The microchip is formed on PMMA substrates by laser ablation and includes a sample zone, a flash distillation zone, a cooling zone, a condensation zone, and a collection zone. In the presented method, the CH2O sample is placed in the microchip and is vaporized by the high-throughput vapor supply and driven through the condensed zone. The condensed CH2O liquid is guided into the collection zone of the microchip. Finally, the distilled CH2O solution is determined using an AHMT spectrometry method and a paper-based RGB (red, green and blue) intensity analysis method. A distilled efficiency is as high as 98%, when a vapor stream rate is 0.4 ml/min and a distilled time is 10 min. Moreover, both detection methods show linear relationships of the corresponding CH2O concentrations. The actual sample suitability of the presented multifunctional microchip-based distillation apparatus is confirmed by analyzing the CH2O concentrations of 21 commodities.

Cost Optimization for On-Demand Content Streaming in IoV Networks With Two Service Tiers

On-demand streaming of high-quality video content is a widely anticipated vehicular infotainment service. How to reduce the cost of content streaming is a primary concern of the service providers, but is still an underinvestigated subject in the literature. This paper proposes an integrated mobile streaming and caching scheme that jointly leverages two communication service tiers and on-board caching resource for cost reduction. Algorithms are presented to achieve optimal buffering at the session level and optimal caching at the device level. An analytical framework is established to characterize the average cost as a function of the streaming rate in a large scale network. Numerical results demonstrate how the “cost-streaming rate” function changes with vehicle density, network congestion level, content length, and average packet transmission time. We learn an important insight that there is a minimum cost threshold even when the streaming rate approaches zero. We also show that the proposed protocol can effectively reduce the overall cost when the network is not congested. Our findings can provide useful guidelines for the business planning and operation of vehicular content streaming services.

On-Chip Optical Vector Quadrature De-Multiplexer Proposal for QAM De-Aggregation by Single Bi-Directional SOA-Based Phase-Sensitive Amplifier

In this paper, a simple optical vector quadrature de-multiplexer (QD) scheme is proposed for de-aggregating input 10 Gbaud 16/32/64 quadrature amplitude modulation (QAM) signals into two pulse amplitude modulation (PAM) streams. The proposed QD is based on a single bi-directional degenerate phase-sensitive amplifier (PSA), where the wavelength and the polarization status of the extracted in-phase and quadrature components stay the same as the input signal. Since the proposed QD is realized using PSA based on semiconductor optical amplifier (SOA), it is also possible to realize an on-chip QD system, providing an integrated platform for optical signal processing. Through numerical simulation, the transfer characteristics of the proposed QD system show that the SOA-based PSA has a high phase-sensitive gain extinction ratio of 44.1 dB. The constellations, error vector magnitudes (EVMs), and bit-error rates (BERs) of the data streams after the de-aggregation are numerically investigated to verify the proposed QD scheme. For the 10 Gbaud 16/32/64 QAM signals with an input optical signal-to-noise ratio (OSNR) of 25 dB, the de-aggregated PAM4/PAM6/PAM8 signals show 6.1, 5.6, and 8.2 dB receiver OSNR improvements at the BER of 10−3, respectively. Also, to optimize the performance of the subsystem, the BER performance dependence on the phase difference between two arms in the subsystem is also examined. The simulation results reveal that the proposed QD can accomplish the function of optical vector de-aggregation well for the high-level QAM signals. The proposed QD can be applied to information de-aggregation, format conversion, and direct detection for optical vector signals, which may have great potential values for the flexible optical networks.

КОДУВАННЯ БІТОВОГО ПРЕДСТАВЛЕННЯ ТРАНСФОРМАНТ У РАМКАХ УПРАВЛІННЯ БІТОВОЮ ШВИДКІСТЮ ВІДЕО

The conceptual basements of constructing an effective encoding method within the bit rate control module of video traffic in the video data processing system at the source level are considered. The essence of using the proposed method in the course of the video stream bit rate controlling disclosed, namely, the principles of constructing the fragment of the frame code representation and approaches for determining the structural units of the individual video frame within which the control is performed. The method focuses on processing the bit representation of the DCT transformants, and at this processing stage transformant was considered as a structural component of the video stream frame at which the encoding is performed. At the same time, to ensure the video traffic bit rate controlling flexibility, decomposition is performed with respect to each of the transformants to the level of the plurality of bit planes. It is argued that the proposed approach is potentially capable to reducing the video stream bit rate in the worst conditions, that is, when component coding is performed. In addition, this principle of video stream fragmen code representation forming allows to control the level of error that can be made in the bit rate control process. However, in conditions where the bit representation of the transformant is encoded, the method is able to provide higher compression rates as a result of the fact that the values ​​of the detection probability of binary series lengths and the values ​​of detected lengths within the bit plane will be greater than in the case of component coding. This is explained by the structural features of the distribution of binary elements within each of the bit planes, which together form the transformer DCT. In particular, high-frequency transformer regions are most often formed by chains of zero elements. The solutions proposed in the development of the encoding method are able to provide sufficient flexibility to control the bit rate of the video stream, as well as the ability to quickly change the bit rate in a wide range of values.

EcoMobiFog–Design and Dynamic Optimization of a 5G Mobile-Fog-Cloud Multi-Tier Ecosystem for the Real-Time Distributed Execution of Stream Applications

The emerging 5G paradigm will enable multi-radio smartphones to run high-rate stream applications. However, since current smartphones remain resource and battery-limited, the 5G era opens new challenges on how to actually support these applications. In principle, the service orchestration capability of the Fog and Cloud Computing paradigms could be an effective means of dynamically providing resource-augmentation to smartphones. Motivated by these considerations, the peculiar focus of this paper is on the joint and adaptive optimization of the resource and task allocations of mobile stream applications in 5G-supported multi-tier Mobile-Fog-Cloud virtualized ecosystems. The objective is the minimization of the computing-plus-network energy of the overall ecosystem under hard constraints on the minimum streaming rate and the maximum computing-plus-networking resources. To this end: 1) we model the target ecosystem energy by explicitly accounting for the virtualized and multi-core nature of the Fog/Cloud servers; 2) since the resulting problem is non-convex and involves both continuous and discrete variables, we develop an optimality-preserving decomposition into the cascade of a (continuous) resource allocation sub-problem and a (discrete) task-allocation sub-problem; and 3) we numerically solve the first sub-problem through a suitably designed set of gradient-based adaptive iterations, while we approach the solution of the second sub-problem by resorting to an ad-hoc-developed elitary Genetic algorithm. Finally, we design the main blocks of EcoMobiFog, a technological virtualized platform for supporting the developed solver. The extensive numerical tests confirm that the energy-delay performance of the proposed solving framework is typically within a few per-cent the benchmark one of the exhaustive search-based solution.

Analysis of Lithium Bromide-Water (LiBr- H2O) Vapour Absorption Refrigeration System Using First Law of Thermodynamics

In the ongoing years, the interest for refrigeration innovation is rising since waste warmth from warm frameworks, for example, control plants or sunlight based vitality can be exhausted for their task. A large portion of the energies are send by the businesses because of consumption of petroleum derivatives and expanding the fuel Price to use the most extreme accessible vitality from the waste warmth sources. Absorption cooling offers the likelihood of utilizing waste heat to give cooling. The goal of this paper is to show observational relations for finding the attributes and execution of a solitary stage Lithium bromide - water (LiBr-H2O) vapor absorption refrigeration system. The fundamental heat and mass exchange conditions and suitable conditions depicting the thermodynamic properties of the working fluid at all thermodynamic states are assessed. The first Law of Thermodynamics is connected to a single stage Lithium Bromide-Water Vapor Absorption Refrigeration framework, and the execution examination of every part is determined through numerical model on MATLAB 7.0.1. First law of thermodynamics is additionally used to ascertain to assessment of mass flow rate and heat rate in every part of the framework. Estimated the thermodynamic properties and Energy transfer rate in every part of Vapor absorption refrigeration system, with the assistance of empirical relation. Mass stream rate and heat flow rate in every segment of the framework are classified. The coefficient of performance of the system is deciding for different temperatures ranges. It very well may be seen that when the temperature of inlet water expands, the required circulation ratio diminishes, and the system COP esteem increments. In the event that the temperature is underneath 58°C, the system COP will be near zero, the system does not work by any means and from 58°C to 83°C, the COP will increment in a slower pace, after 83°C of generator temperature the COP increment quickly.

Controls on fluvial carbon efflux from eroding peatland catchments

AbstractGlobal peatlands store an unparalleled proportion of total global organic carbon but it is vulnerable to erosion into fluvial systems. Fluvial networks are being recognized as areas of carbon transformation, with eroded particulate organic carbon processed to dissolved organic carbon and CO2. Existing studies indicate biodegradation and photodegradation as key processes controlling the transformation of organic carbon in fluvial systems, with initial concentrations of dissolved organic carbon (DOC) identified as a control on the rate of carbon mineralization. This study manipulates temperature and incident light intensity to investigate carbon mineralization rates in laboratory simulations of peatland sediment transport into fluvial systems. By directly measuring gaseous CO2 emissions from sampled stream water, the relationship of temperature and light intensity with carbon efflux is identified. In simulations where sediment (as particulate organic matter, POM) is absent, temperature is consistently the dominant factor influencing carbon efflux rates. This influence is independent of the initial DOC concentration of the water sample. In simulations where POM was added, representing a peatland river receiving eroded terrestrial sediment, initial DOC concentration predicts 79% of the variation in total gaseous carbon efflux whereas temperature and light intensity predict 12% and 3%, respectively. When sampled stream water's mineralization rates in the presence of added POM are analysed independently, removing DOC as a model variable, the dominant variable affecting CO2 efflux is opposite for each sample. This study presents novel data suggesting peatland erosion introduces further complexity to dynamic stream systems where rates of carbon transformation processes and the influence of specific environmental variables are interdependent. Anthropogenic climate change is identified as a leading risk factor perpetuating peatland erosion; therefore, understanding the fate of terrestrial sediment in rivers and further quantifying the benefits of protecting peatland soils will be of increasing importance to carbon budgeting and ecosystem function studies.

The emergence of macroscopic interactions between intersecting pedestrian streams

The interactions between individual pedestrians can lead to emergent effects, such as the formation of lanes in bidirectional flows. Here, we expose properties of an emergent effect at a macroscopic level, namely interactions between pedestrian streams that arise when pedestrians walk into and through four-way intersections from different directions. We propose non-spatial models for the number of pedestrians from different streams inside an intersection. Each model encodes a different hypothesis for how streams interact and can produce dynamics fundamentally distinct from the other models. By fitting our models to large experimental data sets and determining which model explains the data best, we determine when and how entire streams of pedestrians start to interact. We find that as arrival rates increase, streams start to interact and compete for space. Our results suggest that these interactions result in an even balance of pedestrian numbers across two orthogonally intersecting streams. Neither of the streams can dominate. In contrast, for four intersecting streams, our findings suggest that jams in some streams can coincide with higher flow rates in other streams and that the relative dominance of streams can switch stochastically. By adapting existing methodology, we thus present a coherent conceptual approach for investigating emergent effects in temporal dynamics at aggregated levels in pedestrian flows that could be applied to other scenarios. Our approach is flexible and uses easily measured quantities, making it highly suitable for observational data in different scenarios or deployment in applications.

On the Interaction Between Joint Tx/Rx IQI and Channel Estimation Errors in DVB-T Systems

Digital video broadcasting terrestrial (DVB-T) systems use hierarchical modulation, which involve a “high-priority” and a “low-priority” (LP) bit stream. An inherent weakness of this scheme is the severe performance degradation of the less protected LP stream. In addition, the presence of inphase quadrature imbalance (IQI) at both transmitter/receiver front end may significantly reduce the detection accuracy. Here, we propose an improved receiver design for OFDM-based DVB-T systems confronting the effects of both imperfect channel estimation and IQI. First , we propose a specific pilot-symbol arrangement inside the OFDM symbol that facilitates derivation of the posterior distribution of the perfect channel conditioned on its maximum-likelihood (ML) estimate. The latter posterior distribution plays an important role toward an improved receiver design for taking into account channel estimation errors in the presence of IQI at the receiver side. Second , we derive the formulation of an improved and efficient detector under channel estimation errors when IQI is also present only at the receiver side. Third , we generalize our proposed improved detector for the case where IQI is present at both transmitter and receiver sides. The proposed approach is able to reduce the impact of channel uncertainty on the receiver's performance in the presence of IQI. Our results are compared to those achieved by the conventional mismatched ML detector, which uses the imperfect channel as perfect channel and to those obtained by the detector based on the expectation-maximization algorithm. Numerical results over a realistic COST 207 channel model show that significant performance improvement is achieved for bit error rate of the LP stream in the considered DVB-T system.

Comparison of Complication Rates of Central Venous Catheters Versus Peripherally Inserted Central Venous Catheters in Pediatric Patients*

The purpose of our study is to compare the rate of central line-associated blood stream infections and venous thromboembolism in central venous catheters versus peripherally inserted central catheters in hospitalized children. There is a growing body of literature in adults describing an increased rate of venous thromboembolisms and similar rates of central line-associated blood stream infection associated with peripherally inserted central catheters versus central venous catheters. It is not known if the rate of central line-associated blood stream infection and venous thromboembolism differs between peripherally inserted central catheters and central venous catheters in children. Based on current adult literature, we hypothesize that central line-associated blood stream infection rates for peripherally inserted central catheters and central venous catheters will be similar, and the rate of venous thromboembolism will be higher for peripherally inserted central catheters versus central venous catheters. This is a cohort study using retrospective review of medical records and prospectively collected hospital quality improvement databases. Quaternary-care pediatric hospital from October 2012 to March 2016. All patients age 1 day to 18 years old with central venous catheters and peripherally inserted central catheters placed during hospital admission over the study dates were included. Central venous catheters that were present upon hospital admission were excluded. The primary outcomes were rate of central line-associated blood stream infection and rate of venous thromboembolism. None. Of 2,709 catheters included in the study, 1,126 were peripherally inserted central catheters and 1,583 were central venous catheters. Peripherally inserted central catheters demonstrated a higher rate of both infection and venous thromboembolism than central venous catheters in all reported measures. In multivariable analysis, peripherally inserted central catheters had increased association with central line-associated blood stream infection (odds ratio of 3.15; 95% CI, 1.74-5.71; p = 0.0002) and increased association with venous thromboembolism (odds ratio of 2.71; 95% CI, 1.65-4.45; p < 0.0001) compared with central venous catheters. Rates of central line-associated blood stream infection and venous thromboembolism were higher in hospitalized pediatric patients with peripherally inserted central catheters as compared to central venous catheters. Our study confirms the need for further investigation into the safety of central access devices to assist in proper catheter selection.

Experimental and numerical analysis of a nanofluidic thermosyphon heat exchanger

ABSTRACTThermosyphons have high effective thermal conductivity and are applicable for different heat transfer purposes including cooling devices and heat exchangers. In the present study, thermal performance of a thermosyphon is experimentally investigated by using Ni/Glycerol–water nanofluid in three concentrations including 0.416, 0.625 and 1.25 g/lit. Experimental results revealed that using the nanofluid with 0.625 g/lit concentration leads to lowest thermal resistances. Afterwards, a thermosyphon-based heat exchanger is designed and numerically investigated to compare its performance with copper heat exchanger. Since the effective thermal conductivity of thermosyphon depends on temperature difference between condenser and evaporator, a novel approach is applied to achieve precise modeling. Effects of mass flow rates of cold and streams and inlet temperature of hot stream on heat transfer rate are evaluated. Results revealed that using thermosyphon instead of copper tubes with the same dimensions results in more than 100% improvement in heat transfer capacity. Moreover, it is concluded that increase in the mass flow rates of the streams and inlet temperature of hot stream lead to increase in heat transfer rate. A 3D graph is represented to evaluate the influences of hot stream temperature and mass flow rate on the heat transfer rate of thermosyphon-based heat exchanger.