70,131 research outputs found
Recommended from our members
Learning occupantsâ indoor comfort temperature through a Bayesian inference approach for office buildings in United States
A carefully chosen indoor comfort temperature as the thermostat set-point is the key to optimizing building energy use and occupantsâ comfort and well-being. ASHRAE Standard 55 or ISO Standard 7730 uses the PMV-PPD model or the adaptive comfort model that is based on small-sized or outdated sample data, which raises questions on whether and how ranges of occupant thermal comfort temperature should be revised using more recent larger-sized dataset. In this paper, a Bayesian inference approach has been used to derive new occupant comfort temperature ranges for U.S. office buildings using the ASHRAE Global Thermal Comfort Database. Bayesian inference can express uncertainty and incorporate prior knowledge. The comfort temperatures were found to be higher and less variable at cooling mode than at heating mode, and with significant overlapped variation ranges between the two modes. The comfort operative temperature of occupants varies between 21.9 and 25.4 °C for the cooling mode with a median of 23.7 °C, and between 20.5 and 24.9 °C for the heating mode with a median of 22.7 °C. These comfort temperature ranges are similar to the current ASHRAE standard 55 in the heating mode but 2â3 °C lower in the cooling mode. The results of this study could be adopted as more realistic thermostat set-points in building design, operation, control optimization, energy performance analysis, and policymaking
The GEMS Approach to Stationary Motions in the Spherically Symmetric Spacetimes
We generalize the work of Deser and Levin on the unified description of
Hawking radiation and Unruh effect to general stationary motions in spherically
symmetric black holes. We have also matched the chemical potential term of the
thermal spectrum of the two sides for uncharged black holes.Comment: Latex file, 12 pages, no figure; v2: typos fixed; v3: minor
corrections, final version published in JHE
The topologically twisted index of super-Yang-Mills on and the elliptic genus
We examine the topologically twisted index of super-Yang-Mills
with gauge group on , and demonstrate that it receives
contributions from multiple sectors corresponding to the freely acting
orbifolds where . After summing over
these sectors, the index can be expressed as the elliptic genus of a
two-dimensional theory resulting from Kaluza-Klein reduction
on . This provides an alternate path to the 'high-temperature' limit of
the index, and confirms the connection to the right-moving central charge of
the theory.Comment: 29 pages, 1 figure; v2: restricted to real chemical potentials in
section 4 and added a comment on the index where in
section
General one-loop formulas for decay
Radiative corrections to the are evaluated in the
one-loop approximation. The unitary gauge gauge is used. The analytic result is
expressed in terms of the Passarino-Veltman functions. The calculations are
applicable for the Standard Model as well for a wide class of its gauge
extensions. In particular, the decay width of a charged Higgs boson can be derived. The consistence of our formulas and
several specific earlier results is shown.Comment: 33 pages, 3 figures, a new section (V) and references were improved
in the published versio
Recommended from our members
Building thermal load prediction through shallow machine learning and deep learning
Building thermal load prediction informs the optimization of cooling plant and thermal energy storage. Physics-based prediction models of building thermal load are constrained by the model and input complexity. In this study, we developed 12 data-driven models (7 shallow learning, 2 deep learning, and 3 heuristic methods) to predict building thermal load and compared shallow machine learning and deep learning. The 12 prediction models were compared with the measured cooling demand. It was found XGBoost (Extreme Gradient Boost) and LSTM (Long Short Term Memory) provided the most accurate load prediction in the shallow and deep learning category, and both outperformed the best baseline model, which uses the previous day's data for prediction. Then, we discussed how the prediction horizon and input uncertainty would influence the load prediction accuracy. Major conclusions are twofold: first, LSTM performs well in short-term prediction (1 h ahead) but not in long term prediction (24 h ahead), because the sequential information becomes less relevant and accordingly not so useful when the prediction horizon is long. Second, the presence of weather forecast uncertainty deteriorates XGBoost's accuracy and favors LSTM, because the sequential information makes the model more robust to input uncertainty. Training the model with the uncertain rather than accurate weather data could enhance the model's robustness. Our findings have two implications for practice. First, LSTM is recommended for short-term load prediction given that weather forecast uncertainty is unavoidable. Second, XGBoost is recommended for long term prediction, and the model should be trained with the presence of input uncertainty
- âŠ