• Energy Research
• Open Access close
• FR close
• Tsinghua University close

Global warming due to anthropogenic activities has alarming effects on biodiversity. It could negatively impact the interactions between predators and their prey by shifting or eliminating their suitable habitats. The predator common leopard (Panthera pardus) and two prey species, Himalayan grey goral (Naemorhedus goral) and Himalayan grey langur (Semnopithecus ajax) play important roles in balancing the forest ecosystem in northern Pakistan. The common leopard is listed as a Vulnerable species on the IUCN Red List, while grey goral and grey langur are listed as Near Threatened and Endangered respectively. For this study, we used Maximum Entropy Model (MaxEnt) to model the current (average for 1950–2000) and future (in 2070) suitable habitat for each of these species using three General Circulation Models [GCMs; i.e. Beijing Climate Center Climate System Model (BCC-CSM1–1), Community Climate System Model (CCSM4), and Hadley Global Environment Model 2 (HadGEM2-AO)]. We used two climate change emission scenarios, i.e., a moderate carbon emission scenario (RCP4.5) and an extreme carbon emission scenario (RCP8.5). Our results indicated that an area of 18,360 km2, 34,142 km2 and 10,636 km2 are currently suitable for the common leopard, grey goral, and grey langur, respectively. In the future, common leopard, grey goral and grey langur were predicted to lose over 11%, 43%, and 44% of currently inhabited areas under the most severe climate scenario (RCP8.5), respectively. Overall, 56–89% of the current suitable habitat area was predicted as stable suitable habitat for all the species. The study projected that currently, 14,321 km2 is suitable for both common leopard and grey goral. Whereas, 7096 km2 of current habitat is suitable for both common leopard and grey langur. Overlapping areas were predicted to be reduced in the future (due to fluctuations in temperature and precipitation), ranging from 2% (under RCP8.5) to 8% (under RCP45) for areas suitable for common leopard and grey goral, and from 30% (under RCP4.5) to 47% (under RCP8.5) for areas suitable for common leopard and grey langur, respectively. Most of the overlapping areas that remained suitable were projected between the altitudinal range of 1000 m – 3000 m for common leopard and grey goral, and from 2000 m to 4000 m for common leopard and grey langur. Our results inform management plans and conservation strategies (e.g., establishment of new or improving the status of existing protected areas) for mitigating the impacts of climate change on endangered predator and prey species in the northern Pakistan.

A search is presented for new physics in events with two low-momentum, oppositely charged leptons (electrons or muons) and missing transverse momentum in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data collected using the CMS detector at the LHC correspond to an integrated luminosity of 35.9. The observed event yields are consistent with the expectations from the standard model. The results are interpreted in terms of pair production of charginos and neutralinos (X1 and X2) with nearly degenerate masses, as expected in natural supersymmetry models with light higgsinos, as well as in terms of the pair production of top squarks (t), when the lightest neutralino and the top squark have similar masses. At 95% confidence level, wino-like X1/X2 masses are excluded up to 230 GeV for a mass difference of 20 GeV relative to the lightest neutralino. In the higgsino-like model, masses are excluded up to 168 GeV for the same mass difference. For pair production, top squark masses up to 450 GeV are excluded for a mass difference of 40 GeV relative to the lightest neutralino. Physics Letters B, 782 ISSN:0370-2693 ISSN:0031-9163 ISSN:1873-2445

Abstract Global temperatures are predicted to rise from between 1.4 to 5.8°C by 21st century, which could result in a 20 to 30% extinction of species. The negative impacts of climate change on the northern highlands of Pakistan (NHP) could change the species composition. Range shifts and range reduction in the forested landscapes will dramatically affect the distribution of forest dwelling species, including the Galliformes (ground birds). Three Galliformes (e.g., Lophophorus impejanus, Pucrasia macrolopha and Tragopan melanocephalus) are indicator species of the environment and currently distributed in NHP. For this study, we used Maximum Entropy Model (MaxEnt) to simulate the current and future (in 2050 and 2070) distributions of the species using three General Circulation Models (GCMs) and two climate change scenarios, i.e., RCP4.5 (moderate carbon emission scenario) and RCP8.5 (peak carbon emission scenario). Our results indicated that (i) all the three species would be negatively affected by the climate change in 2050 and in 2070. (ii) Under all three climate scenarios, species distribution was predicted to both reduce and shift towards higher altitudes. (iii) Across the provinces in the NHP, the species were predicted to lose over one quarter in 2050 and one-third by 2070 of the current suitable habitat. (iv) The maximum area of climate refugia was projected between the altitudinal range of 2000 m to 4000 m and predicted to shift towards higher altitudes primarily >3000 m in the future. The proposed implications such as establishment and upgradation of the protected areas, ban on hunting, timber mafia and temporary settlements of the local people in the forested landscapes should be under special consideration to mitigate the impact of climate change.

Abstract Thermal bridges losses represent an increasing part of heat losses owing to significant three-dimensional heat transfer characteristics in modern buildings, but one-dimensional models are used in most simulation software for thermal analyses to simplify the calculations. State model reduction techniques were used to develop low-order three-dimensional heat transfer model for additional losses of thermal bridges, which is efficient and accuracy. Coupling this technique with traditional one-dimensional model for walls losses, it is possible to reduce a large amount of time simulations. Low-order model was validated from frequency response and time-domain output. And the effect of this model was shown with its implementation in software “TRNSYS”.

Abstract Variable refrigerant flow (VRF) air conditioning system is widely used in commercial buildings for space cooling and heating. However, some VRF systems used in high-rise buildings cannot work efficiently or even stop working because of the relatively high ambient air temperature, caused by the thermal plume effect of exhaust heat from outdoor units. In this paper, the thermal plume air flow of the layer-based VRF systems is investigated through computational fluids dynamics (CFD) simulation. Moreover, an illustrative example of practical VRF system in a 30-storey office building in Shenzhen is analyzed to optimize the layout of the outdoor units. Preliminary results show that the exhaust heat of outdoor units can cause ascending thermal plume flow, leading to higher inlet temperatures for VRF air conditioners on upper floors, even exceeding the warning upper threshold value. It also indicates that enlarging the distance between outdoor units on different floors is an effective way to impair the thermal plume effect for VRF outdoor units and improve the thermal performance of the whole system. For the studied case, the average inlet temperatures can be decreased by 22% for VRF outdoor units with floor interval. This work can provide guidance for the optimization layout design of practical VRF air conditioning systems used in high-rise buildings.