Optimal dispersion management for a wavelength division multiplexedoptical soliton transmission system

Soliton's frequency shift arising from the pulse collision between wavelength division multiplexed (WDM) channels in an optical transmission line may be reduced by dispersion management technique. The reduction mechanism is due to a cancellation between the shifts in normal and anomalous dispersion fibers. With a proper management of the dispersion, the effect of lumped amplifiers on the frequency shift may also be canceled out. In this paper, we give a detailed analysis of the frequency shift in dispersion managed systems, and explain the reduction mechanism of the shift. We then propose optimal dispersion management schemes by means of minimizing the frequency shift. We also present a statistical analysis of the collision induced timing jitter for a two-channel WDM system     

Pathophysiology and Treatment of Diabetic Cardiomyopathy and Heart Failure in Patients with Diabetes Mellitus

There is a close relationship between diabetes mellitus and heart failure, and diabetes is an independent risk factor for heart failure. Diabetes and heart failure are linked by not only the complication of ischemic heart disease, but also by metabolic disorders such as glucose toxicity and lipotoxicity based on insulin resistance. Cardiac dysfunction in the absence of coronary artery disease, hypertension, and valvular disease is called diabetic cardiomyopathy. Diabetes-induced hyperglycemia and hyperinsulinemia lead to capillary damage, myocardial fibrosis, and myocardial hypertrophy with mitochondrial dysfunction. Lipotoxicity with extensive fat deposits or lipid droplets is observed on cardiomyocytes. Furthermore, increased oxidative stress and inflammation cause cardiac fibrosis and hypertrophy. Treatment with a sodium glucose cotransporter 2 (SGLT2) inhibitor is currently one of the most effective treatments for heart failure associated with diabetes. However, an effective treatment for lipotoxicity of the myocardium has not yet been established, and the establishment of an effective treatment is needed in the future. This review provides an overview of heart failure in diabetic patients for the clinical practice of clinicians.     

Immunostimulatory effects of water extract from bulbus arteriosus in tuna in vitro

Immunostimulating effects of water extract from bulbus arteriosus in tuna were examined and found to enhance IgM production by human hybridoma HB4C5 cells. When tuna bulbus arteriosus extract was heated, the IgM production-stimulating activity was decreased or lost. To identify the active substance, the extract was partially purified by anion-exchange chromatography, and proteins contained in positive fractions were analyzed by LC-MS/MS. The positive fractions contained lactate dehydrogenase, triosephosphate isomerase, enolase, and haemoglobin. Each of these four proteins was verified to enhance IgM production by HB4C5 cells with the commercially available purified proteins, suggesting that all of these four proteins are active substances in the extract. The immunostimulatory effect of these proteins was also examined on mouse primary spleen lymphocytes in vitro. Lactate dehydrogenase enhanced IgA, IgG, and IgM production and triosephosphate isomerase enhanced IgA and IgG production. In particular, lactate dehydrogenase had the strongest Ig production-stimulating effect on HB4C5 cells and on mouse primary lymphocytes. Thus, fish viscera may serve as an important raw material for the enhancement of the acquired immune system, once processed.     

Hybrid adsorption cooling systems–An overview

With sharp rising global energy demand posing a rapid development in sustainable cooling systems is required. Hybrid adsorption cooling cycle is considered as one of the sustainable cooling systems. The present study introduces a survey of hybrid adsorption cooling systems in order to stand on its fact and clarify the future trend. The survey sectioned the hybrid adsorption systems into three sections; (i) assisted technology, (ii) application, and (iii) heat source type. The hybrid system which uses vapor compression with adsorption employing activated carbon/CO₂ pair was found to have the highest value of the coefficient of performance (COP). On the contrary, vapor compression-hybrid cooling system using activated carbon/R134a as the adsorbent/refrigerant pair has the lowest COP value and substantial research development and demonstration (RD&D) is required to meet the global challenge of energy conservation.     

A Study on Characteristics of Cooling Heat Transfer of Supercritical Pressure Fluids in a Plate Heat Exchanger

For the development of industrial heat pump systems supplying a high-temperature heat source over 130°C, experiments were carried out on cooling heat transfer of supercritical pressure fluids flowing in a plate heat exchanger (PHE). Using two refrigerants of HFC134a and HCFC22 as the test fluids, heat transfer coefficient data were obtained at different pressure, flow rate, and heat load conditions. The heat transfer coefficient generally had a maximum in the vicinity of the pseudocritical point and showed seven- to ninefold values compared with tube flow. Based on the measurements, characteristics of cooling heat transfer of supercritical pressure fluids in the PHE were clarified and a correlation of heat transfer coefficient was developed.     

Boiling Heat Transfer and Pressure Drop of a Refrigerant R32 Flowing in a Small Horizontal Tube

In this study, experiments were performed to examine characteristics of flow boiling heat transfer and pressure drop of a low global warming potential refrigerant R32 flowing in a horizontal copper circular tube with 1.0 mm inside diameter for the development of a high-performance heat exchanger using small-diameter tubes or minichannels for air conditioning systems. Axially local heat transfer coefficients were measured in the range of mass fluxes from 30 to 400 kg/(m²·s), qualities from 0.05 to 1.0, and heat fluxes from 2 to 24 kW/m² at the saturation temperature of 10°C. Pressure drops were also measured in the rage of mass fluxes from 30 to 400 kg/(m²·s) and qualities from 0.05 to 0.9 at the saturation temperature of 10°C under adiabatic condition. In addition, two-phase flow patterns were observed through a sight glass fixed at the tube exit with a digital camera. The characteristics of boiling heat transfer and pressure drop were clarified based on the measurements and the comparison with data of R410A obtained previously. Also, measured heat transfer coefficients were compared with two existing correlations.     

The flow characteristics of an upward gas‐liquid two‐phase flow in a vertical tube with a wire coil: Part 2. Effect on void fraction and liquid film thickness

An experimental study has been carried out to clarify the characteristics of the void fraction and the liquid film thickness of the air‐water two‐phase flow in vertical tubes of 25‐mm inside diameter with wire coils of varying wire diameter and pitch. The flow pattern in the experiment on the average void fraction and the local void fraction distribution in cross section was a bubble flow, and the liquid film thickness was in the region of semiannular and annular flows. It is clarified from these experiments that the average void fraction in tubes with wire coils is lower than that in a smooth tube and decreases with the wire diameter owing to the centrifugal force of the swirl flow which concentrates bubbles at the center of the tube, that the local liquid film thickness becomes more uniform with a decrease in the pitch of the wire coil, and that the liquid film becomes thicker after the passage through the wire coil with an increase in the wire diameter. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(8): 652–664, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10067     

Optimisation of two-stage Raman converter based on phosphosilicatecore fibre: modelling and experiment

Parameter optimisation of a two-stage Raman converter based on phosphosilicate-core fibre is presented. The optimal operational regime is determined and its tolerance against variations of laser parameters is examined. Results of numerical modelling are in a good agreement with experimental data