Second order closure modeling of turbulent buoyant wall plumes

Non-intrusive measurements of scalar and momentum transport in turbulent wall plumes, using a combined technique of laser Doppler anemometry and laser-induced fluorescence, has shown some interesting features not present in the free jet or plumes. First, buoyancy-generation of turbulence is shown to be important throughout the flow field. Combined with low-Reynolds-number turbulence and near-wall effect, this may raise the anisotropic turbulence structure beyond the prediction of eddy-viscosity models. Second, the transverse scalar fluxes do not correspond only to the mean scalar gradients, as would be expected from gradient-diffusion modeling. Third, higher-order velocity-scalar correlations which describe turbulent transport phenomena could not be predicted using simple turbulence models. A second-order closure simulation of turbulent adiabatic wall plumes, taking into account the recent progress in scalar transport, near-wall effect and buoyancy, is reported in the current study to compare with the non-intrusive measurements. In spite of the small velocity scale of the wall plumes, the results showed that low-Reynolds-number correction is not critically important to predict the adiabatic cases tested and cannot be applied beyond the maximum velocity location. The mean and turbulent velocity profiles are very closely predicted by the second-order closure models. but the scalar field is less satisfactory, with the scalar fluctuation level underpredicted. Strong intermittency of the low-Reynolds-number flow field is suspected of these discrepancies. The trends in second- and third-order velocity-scalar correlations, which describe turbulent transport phenomena, are also predicted in general, with the cross-streamwise correlations better than the streamwise one. Buoyancy terms modeling the pressure-correlation are shown to improve the prediction slightly. The effects of equilibrium time-scale ratio and boundary condition are also discussed

Knowledge-Based Clubhouse Adoption Intention in the Post-COVID-19 Era in the Hospitality Industry

The COVID-19 pandemic has affected the digital transformation of the hospitality industry and triggered Clubhouse knowledge adoption behavior. Clubhouse engagement in the COVID-19 era has gradually changed the forms of communication. Hospitality industry owners can communicate about their interactions and trades through Clubhouse, and members can share their operating and management experiences. Therefore, hospitality industry owners can learn from and support each other. This study aims to bridge the gap between professional knowledge and management adoption in the community of hospitality industry owners. We treat members’ self-regulated and socially regulated learning styles as variables in our analysis of members’ behaviors after acquiring knowledge from the community. This study contributes to our understanding of knowledge-based digital transformation processes in the hospitality industry in the post-COVID-19 era. It has implications for both Clubhouse users and hosts

A New Seamless Bitstream Switching Scheme for H.264 Video Adaptation with Enhanced Coding Performance

[[abstract]]In this paper, we propose a new seamless bitstream switching scheme to improve the coding performance of H.264 SP-frames for rate adaptation. Our method removes one of the two re-quantization blocks in the SP-frame encoders so as to significantly improve coding performance. The seamless switching property of SP-frames is retained by properly restructuring the primary and secondary switching frame codecs. Experimental results show that our proposed scheme achieves close coding performance to that of regular H.264 P-frames and significantly better performance than that of SP-frames. The proposed method also provides the advantage of using a single secondary switching bitstream for both switching-up and switching-down processes[[fileno]]2030144030014[[department]]電機工程學

Modeling the Combined Effects of River Stage and Groundwater Flow on Riverbank Stability Before and After Dam Removal

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

The Influence of Type 2 Diabetes and Glucose-Lowering Therapies on Cancer Risk in the Taiwanese

Objective. To investigate the association between type 2 diabetes, glucose-lowering therapies (monotherapy with either metformin, sulphonylurea or insulin) and cancer risk in Taiwan. Methods. Using Taiwan's National Health Research Institutes database of 1,000,000 random subjects from 2000–2008, we found 61777 patients with type 2 diabetes (age ≥20 years) and 677378 enrollees with no record of diabetes. Results. After adjusting for age and sex, we found patients with diabetes to have significantly higher risk of all cancers (OR: 1.176; 95% CI: 1.149–1.204, P < 0.001). Diabetic patients treated with insulin or sulfonylureas had significantly higher risk of all cancers, compared to those treated with metformin (OR: 1.583; 95% CI: 1.389–1.805, P < 0.001 and OR: 1.784; 95% CI: 1.406–2.262, P < 0.001). Metformin treatment was associated with a decreased risk of colon and liver cancer compared to sulphonylureas or insulin treatment. Sulfonylureas treatment was associated with an increased risk of breast and lung cancer compared to metformin therapy. Conclusions. Taiwanese with type 2 diabetes are at a high risk of breast, prostate, colon, lung, liver and pancreatic cancer. Those treated with insulin or sulfonylureas monotherapy are more likely to develop colon and liver cancer than those treated with metformin

Percutaneous Endoscopic Gastrostomy in the Enteral Feeding of the Elderly

SummaryToday we are faced with an aging society that may develop malnutrition because of dysphagia related to dementia, stroke, and malignancy seen often in the elderly. The preferred form of nutritional supplementation for this group is enteral nutrition, and the most appropriate long-term method is by use of a gastrostomy. Percutaneous endoscopic gastrostomy (PEG) was first introduced in 1980 as an alternative to the traditional operative procedure and rapidly became the preferred procedure. In geriatric patients, the principal indications are neurological dysphagia and malnutrition, related to an underlying disease or anorexia-cachexia in very elderly. PEG is contraindicated in the presence of respiratory distress, previous gastric resection, total esophageal obstruction, coagulation disorders and sepsis in the elderly. Common complications include wound infection, leakage, hemorrhage, and fistula in the general population, but aspiration pneumonia is the major case of death in this group. Risks and complications of PEG must be discussed with patients and their families; and the decision for percutaneous endoscopic gastrostomy insertion should only be made after careful consideration and discussion between managing physicians, allied health professionals, and the patient and/or family. Four ethical principles may help make feeding decisions: beneficence, non-maleficence, autonomy and justice. Attentive long-term care after tube replacement is mandatory. Acceptance of percutaneous endoscopic gastrostomy placement by patients and their families tends to increase once favorable outcomes are offered

Peculiar optical properties of bilayer silicene under the influence of external electric and magnetic fields

We conduct a comprehensive investigation of the effect of an applied electric field on the optical and magneto-optical absorption spectra for AB-bt (bottom-top) bilayer silicene. The generalized tightbinding model in conjunction with the Kubo formula is efficiently employed in the numerical calculations. The electronic and optical properties are greatly diversified by the buckled lattice structure, stacking configuration, intralayer and interlayer hopping interactions, spin-orbital couplings, as well as the electric and magnetic fields (Ez ˆz & Bz ˆz ). An electric field induces spin-split electronic states, a semiconductor-metal phase transitions and the Dirac cone formations in different valleys, leading to the special absorption features. The Ez-dependent low-lying Landau levels possess lower degeneracy, valley-created localization centers, peculiar distributions of quantum numbers, well-behaved and abnormal energy spectra in Bz-dependencies, and the absence of anti-crossing behavior. Consequently, the specific magneto-optical selection rules exist for diverse excitation categories under certain critical electric fields. The optical gaps are reduced as Ez is increased, but enhanced by Bz, in which the threshold channel might dramatically change in the former case. These characteristics are in sharp contrast with those for layered graphene