Experimental investigation of entropy waves' evolution for understanding of indirect combustion noise in gas turbine combustors

Achieving clean and quiet combustion in gas turbines is essential for improving many low-carbon energy and propulsion technologies. This often requires suppression of combustion instabilities and combustion generated noise in gas turbine combustors. Entropy noise is the less explored mechanism of combustion generated sound. Central to the emission of entropic sound is the survival of entropy wave during convection by the mean flow and reaching the combustor exit nozzle. Yet, the annihilation of entropy waves in this process is still poorly understood. To address this issue, the evolution of convected entropy waves in a fully-developed, cold flow inside a circular duct is investigated experimentally. Entropy waves are produced by a well-controlled electrical heater. Fast-response, miniaturized thermocouples arranged over a moveable cross-section of the duct are employed to record the state of entropy waves at different axial locations along the duct. Hydrodynamic parameters including Reynolds number and turbulence intensity are varied to investigate their effects upon the wave decay. The results show that the decay process is strongly wavelength dependent. It is found that the wave components with wavelengths larger than the duct diameter are almost unaffected by the flow and therefore remain essentially one-dimensional. However, other spectral components of the wave are subject to varying degrees of dissipation and loss of spatial correlation. Overall, the results support the recent numerical findings about the likelihood of wave survival in adiabatic flows. They further clarify the validity range of the one-dimensional assumption commonly made in the literature

Von Willebrand disease: gaining a global perspective

Introduction Recent guidelines for von Willebrand Disease (VWD) highlighted the challenges in diagnosis and management. Identifying the number of persons with VWD (PwVWD) internationally will help target support to aid diagnosis of PwVWD. Aim To examine international registration rates of PwVWD, the influence of income status, geographical region and the age and sex profile. Cumulatively, these data will be used to inform future strategy from the World Federation of Haemophilia (WFH) to address unmet clinical and research needs. Methods Data from the 2018/2019 WFH Annual Global Survey (AGS) were analysed, providing a global perspective on VWD registration. Results Registration rates are lowest in South Asia (0.6/million population) and highest in Europe/Central Asia (50.9/million population, 0.005%), but below the expected prevalence rate (0.1%). National economic status impacted VWD registration rates, reflecting variation in access to optimal healthcare infrastructure. Females represented the majority of PwVWD globally, however, in low-income countries (LIC) males predominated. Age profile varied, with markedly higher rates of paediatric registrations in North America, Middle East and North Africa and South Asia. Rates of type 3 VWD registrations were significantly influenced by economic status (81% of VWD diagnoses in LIC), suggesting only the most severe VWD types are diagnosed in resource limited settings. Conclusion Significant variation in registration rates of PwVWD exist internationally and is influenced by income status and the presence of HTC networks. Improved understanding of registration rates will enable targeting of advocacy to improve awareness, diagnosis and support for PwVWD internationally. Key points Registration rates of People with Von Willebrand Disease (PwVWD) vary internationally and are influenced by national income status Although females represent the majority of PwVWD globally, in low income countries (LIC) males predominated, possibly related to stigma surrounding gynaecological bleeding. Rates of type 3 VWD registration were significantly influenced by economic status (81% of VWD diagnoses in LIC), suggesting only the most severe VWD types are diagnosed in resource limited settings

SDLoad

We propose a unified approach for workload generation to ease evaluation and comparison of SDN control-plane proposals. Our approach is based on SDLoad, an extensible framework capable of generating custom workloads satisfying input constraints, along user-defined evaluation axes

Views of patients undergo hematopoietic stem cell transplantation on their basic needs

Background: Today, hematopoietic stem cells transplantation (HSCT) has been accepted as a therapeutic approach and is widely applied in many patients with disorders of hematopoietic systems or patients with malignancies. Concomitant use of this therapeutic approach with long term chemotherapeutic procedures and hospitalization requires special care. This study was conducted to examine basic needs of patients after HSCT. Methods: In this study, 171 hospitalized patients were selected after transplantation, using convenience sampling method. They completed a questionnaire formulated on the basis of Yura and Walsh Theory of Basic Needs. Results: Most of the needs reported in the areas of vital functions, functional health status, and reaction to functional health status were chills (76.8), insomnia (68.5), and dissatisfaction with changes of lifestyle/habits (53.6), respectively. Furthermore, 94.1 of the patients were aware of their disease. Conclusion: This study identified a broad spectrum of the needs in HSCT patients. Given the importance of determining needs to reach a thorough nursing care, paying attention to the provided list can facilitate the achievement of the goals of the care program for these patients