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Abstract In energy demand forecasting, the objective function is often symmetric, implying that over-prediction errors and under-prediction errors have the same consequences. In practice, these two types of errors generally incur very different costs. To accommodate this, we propose a machine learning algorithm with a cost-oriented asymmetric loss function in the training procedure. Specifically, we develop a new support vector regression incorporating a linear-linear cost function and the insensitivity parameter for sufficient fitting. The electric load data from the state of New South Wales in Australia is used to show the superiority of our proposed framework. Compared with the basic support vector regression, our new asymmetric support vector regression framework for multi-step load forecasting results in a daily economic cost reduction ranging from 42.19 % to 57.39 % , depending on the actual cost ratio of the two types of errors.

Estimating how much is appropriate to consume can be difficult, especially for foods presented in multiple units, those with ambiguous energy content and for snacks. This study tested the hypothesis that the number of units (single vs. multi-unit), meal type and food energy density disrupts accurate estimates of portion size. Thirty-two healthy weight men and women attended the laboratory on 3 separate occasions to assess the number of portions contained in 33 foods or beverages of varying energy density (1.7-26.8 kJ/g). Items included 12 multi-unit and 21 single unit foods; 13 were labelled "meal", 4 "drink" and 16 "snack". Departures in portion estimates from reference amounts were analysed with negative binomial regression. Overall participants tended to underestimate the number of portions displayed. Males showed greater errors in estimation than females (p=0.01). Single unit foods and those labelled as 'meal' or 'beverage' were estimated with greater error than multi-unit and 'snack' foods (p=0.02 and p<0.001 respectively). The number of portions of high energy density foods was overestimated while the number of portions of beverages and medium energy density foods were underestimated by 30-46%. In conclusion, participants tended to underestimate the reference portion size for a range of food and beverages, especially single unit foods and foods of low energy density and, unexpectedly, overestimated the reference portion of high energy density items. There is a need for better consumer education of appropriate portion sizes to aid adherence to a healthy diet.

Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the intensity of invertebrate herbivory on a common tundra plant, the dwarf birch (Betula glandulosa-nana complex), and investigated its relationship to latitude and climate across the tundra biome. Leaf damage by defoliating, mining and gall-forming invertebrates was measured in samples collected from 192 sites at 56 locations. Our results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low intensity. On average, invertebrates damaged 11.2% of the leaves and removed 1.4% of total leaf area. The damage was mainly caused by external leaf feeders, and most damaged leaves were only slightly affected (12% leaf area lost). Foliar damage was consistently positively correlated with mid-summer (July) temperature and, to a lesser extent, precipitation in the year of data collection, irrespective of latitude. Our models predict that, on average, foliar losses to invertebrates on dwarf birch are likely to increase by 6--7% over the current levels with a 1 textdegreeC increase in summer temperatures. Our results show that invertebrate herbivory on dwarf birch is small in magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory should be included in predictions of climate change impacts on tundra ecosystems.

We quantify the conditions that might trigger wide spread adoption of alternative fuel vehicles (AFVs) to support energy policy. Empirical review shows that early adopters are heterogeneous motivated by financial benefits, environmental appeal, new technology, and vehicle reliability. A probabilistic Monte Carlo simulation model is used to assess consumer heterogeneity for early and mass market adopters. For early adopters full battery electric vehicles (BEVs) are competitive but unable to surpass diesels or hybrids due to purchase price premium and lack of charging availability. For mass adoption, simulations indicate that if the purchase price premium of a BEV closes to within 20% of an in-class internal combustion engine (ICE) vehicle, combined with a 60% increase in refuelling availability relative to the incumbent system, BEVs become competitive. But this depends on a mass market that values the fuel economy and CO2 reduction benefits associated with BEVs. We also find that the largest influence on early adoption is financial benefit rather than pro-environmental behaviour suggesting that AFVs should be marketed by appealing to economic benefits combined with pro-environmental behaviour to motivate adoption. Monte Carlo simulations combined with scenarios can give insight into diffusion dynamics for other energy demand-side technologies.

Analyse numerique et etude experimentale de l'influence du rapport des temperatures d'une plaque et du fluide sur le nombre de Nusselt d'une couche limite turbulente compressible

De nouveaux systèmes de refroidissement renouvelables sont nécessaires dans le monde entier pour répondre à la demande croissante de refroidissement. Cette étude propose et démontre une nouvelle intégration du refroidissement par absorption solaire avec le stockage de chaleur latente afin de maximiser l'utilisation de l'énergie renouvelable pour le refroidissement dans des climats extrêmement chauds. Une analyse paramétrique a été réalisée dans TRNSYS pour identifier les paramètres critiques pour un dimensionnement optimal liés à la taille du champ solaire, au volume du réservoir, à l'isolation du réservoir, au point de consigne de chauffage auxiliaire et à l'angle d'inclinaison du collecteur. De plus, l'intégration a été comparée à un système de refroidissement par absorption solaire conventionnel utilisant un stockage de chaleur sensible (un réservoir d'eau chaude) et un système de refroidissement par compression de vapeur électrique. Les résultats montrent qu'une taille de champ solaire de 1,5 m2/kWc, un volume de réservoir de stockage de chaleur latente de 30 L/m2, une isolation adéquate inférieure à 0,8 W/m2.K et des températures de consigne appropriées pour la chaudière auxiliaire fournissent les performances optimales pour maximiser la fraction solaire. Par rapport au refroidissement par absorption solaire conventionnel, l'étude démontre comment le matériau à changement de phase (PCM) a augmenté la fraction solaire de 4,2 % (de 70,3 à 74,5 %) en raison d'une température stable plus élevée et de pertes de réservoir plus faibles (réduites de 44 %). En outre, malgré le coût d'investissement initial plus élevé du système de refroidissement solaire à base de PCM proposé par rapport au système de refroidissement par compression de vapeur, les résultats soulignent que le coût du cycle de vie est beaucoup plus faible dans les climats extrêmement chauds. Après 25 ans, le coût du cycle de vie a été réduit de 34 % par rapport à la compression de vapeur et de 9 % par rapport à un système de refroidissement solaire conventionnel. Par rapport à la technologie de réfrigérant à compression de vapeur, le système proposé peut économiser 31,6 % d'énergie primaire et 1 222 kg de CO2eq par an. Cette recherche fournit des informations précieuses sur la conception et l'intégration optimales du refroidissement renouvelable pour les applications résidentielles dans les régions extrêmement chaudes. Se requieren nuevos sistemas de refrigeración renovables en todo el mundo para hacer frente a la creciente demanda de refrigeración. Este estudio propone y demuestra una nueva integración de la refrigeración por absorción solar con el almacenamiento de calor latente para maximizar el uso de energía renovable para la refrigeración en climas extremadamente cálidos. Se realizó un análisis paramétrico en TRNSYS para identificar los parámetros críticos para el dimensionamiento óptimo relacionados con el tamaño del campo solar, el volumen del tanque, el aislamiento del tanque, el punto de ajuste de la calefacción auxiliar y el ángulo de inclinación del colector. Además, la integración se comparó con un sistema de enfriamiento por absorción impulsado por energía solar convencional que utiliza almacenamiento de calor sensible (un tanque de agua caliente) y un sistema de enfriamiento por compresión de vapor impulsado por electricidad. Los resultados muestran que un tamaño del campo solar de 1,5 m2/kWc, un volumen del tanque de almacenamiento de calor latente de 30 L/m2, un aislamiento adecuado por debajo de 0,8 W/m2.K y temperaturas de consigna adecuadas para la caldera auxiliar proporcionan el rendimiento óptimo para maximizar la fracción solar. En comparación con el enfriamiento por absorción solar convencional, el estudio demuestra cómo el material de cambio de fase (PCM) aumentó la fracción solar en un 4,2 % (de 70,3 a 74,5 %) debido a una mayor temperatura estable y menores pérdidas del tanque (reducidas en un 44 %). Además, a pesar del mayor coste de inversión inicial del sistema de refrigeración solar basado en PCM propuesto en comparación con el sistema de refrigeración por compresión de vapor, los hallazgos destacan que el coste del ciclo de vida es mucho menor en climas extremadamente cálidos. Después de 25 años, el coste del ciclo de vida se redujo en un 34 % en comparación con la compresión de vapor y en un 9 % en comparación con un sistema de refrigeración convencional impulsado por energía solar. En comparación con la tecnología de refrigerante por compresión de vapor, el sistema propuesto puede ahorrar el 31,6 % de la energía primaria y 1222 kgCO2eq al año. Esta investigación proporciona información valiosa sobre el diseño y la integración óptimos de la refrigeración renovable para aplicaciones residenciales en regiones extremadamente calurosas. Novel renewable cooling systems are required worldwide to address the growing demand for cooling. This study proposes and demonstrates a novel integration of solar-driven absorption cooling with latent heat storage to maximise the use of renewable energy for cooling in extremely hot climates. A parametric analysis was performed in TRNSYS to identify the critical parameters for optimal sizing related to the solar field size, tank volume, tank insulation, auxiliary heating set point, and collector tilt angle. Moreover, the integration was compared with a conventional solar-driven absorption cooling system using sensible heat storage (a hot water tank) and an electric-driven vapour compression cooling system. The results show that a solar field size of 1.5 m2/kWc, a latent heat storage tank volume of 30 L/m2, adequate insulation below 0.8 W/m2.K, and appropriate set-point temperatures for the auxiliary boiler provide the optimal performance to maximise the solar fraction. Compared with conventional solar-driven absorption cooling, the study demonstrates how the phase change material (PCM) increased the solar fraction by 4.2 % (from 70.3 to 74.5 %) due to higher stable temperature and lower tank losses (reduced by 44 %). In addition, despite the higher initial investment cost of the proposed PCM-based solar-driven cooling system compared to the vapour compression cooling system, the findings highlight that the life cycle cost is much lower in extremely hot climates. After 25 years, the life cycle cost was lowered by 34 % compared to vapour compression and by 9 % compared to a conventional solar-driven cooling system. Compared to vapour compression refrigerant technology, the proposed system can save 31.6 % of primary energy and 1222 kgCO2eq annually. This research provides valuable insights into the optimal design and integration of renewable cooling for residential applications in extremely hot regions. هناك حاجة إلى أنظمة تبريد متجددة جديدة في جميع أنحاء العالم لتلبية الطلب المتزايد على التبريد. تقترح هذه الدراسة وتوضح تكاملًا جديدًا للتبريد بالامتصاص المدفوع بالطاقة الشمسية مع التخزين الحراري الكامن لتعظيم استخدام الطاقة المتجددة للتبريد في المناخات الحارة للغاية. تم إجراء تحليل بارامتري في TRNSYS لتحديد المعلمات الحرجة للتحجيم الأمثل المتعلق بحجم الحقل الشمسي وحجم الخزان وعزل الخزان ونقطة ضبط التسخين الإضافية وزاوية إمالة المجمع. علاوة على ذلك، تمت مقارنة التكامل مع نظام تبريد الامتصاص التقليدي الذي يعمل بالطاقة الشمسية باستخدام تخزين الحرارة المعقول (خزان الماء الساخن) ونظام تبريد ضغط البخار الذي يعمل بالكهرباء. تظهر النتائج أن حجم الحقل الشمسي 1.5 متر مربع/كيلو واط مكعب، وحجم خزان تخزين الحرارة الكامن 30 لتر/متر مربع، والعزل الكافي أقل من 0.8 واط/متر مربع، ودرجات حرارة نقطة الضبط المناسبة للغلاية المساعدة توفر الأداء الأمثل لتحقيق أقصى قدر من الجزء الشمسي. مقارنة بالتبريد بالامتصاص التقليدي القائم على الطاقة الشمسية، توضح الدراسة كيف زادت مادة تغيير الطور (PCM) من الجزء الشمسي بنسبة 4.2 ٪ (من 70.3 إلى 74.5 ٪) بسبب ارتفاع درجة الحرارة المستقرة وانخفاض خسائر الخزان (انخفضت بنسبة 44 ٪). بالإضافة إلى ذلك، على الرغم من ارتفاع تكلفة الاستثمار الأولي لنظام التبريد المقترح القائم على الطاقة الشمسية PCM مقارنة بنظام تبريد ضغط البخار، فإن النتائج تسلط الضوء على أن تكلفة دورة الحياة أقل بكثير في المناخات الحارة للغاية. بعد 25 عامًا، انخفضت تكلفة دورة الحياة بنسبة 34 ٪ مقارنة بضغط البخار وبنسبة 9 ٪ مقارنة بنظام التبريد التقليدي الذي يعمل بالطاقة الشمسية. بالمقارنة مع تقنية تبريد ضغط البخار، يمكن للنظام المقترح توفير 31.6 ٪ من الطاقة الأولية و 1222 كجم من مكافئ ثاني أكسيد الكربون سنويًا. يوفر هذا البحث رؤى قيمة حول التصميم الأمثل ودمج التبريد المتجدد للتطبيقات السكنية في المناطق شديدة الحرارة.

AbstractThe majority of species display strongly asymmetric responses to climatic variables, yet most analytic models used to investigate how species will respond to climate change assume symmetric responses, with largely unknown consequences. Applying a known mapping of population dynamical equations onto corresponding well-studied problems from quantum mechanics, we extend analytical results to incorporate this asymmetry. We derive expressions in terms of parameters representing climate velocity, dispersal rate, maximum growth rate, niche width, high-frequency climate variability, and environmental performance curve skew for three key responses: (1) population persistence, (2) lag between range displacement and climate displacement, and (3) location of maximum population sensitivity. We find that asymmetry impacts these climate change responses, but surprisingly, under our model assumptions, the direction (i.e., warm skewed or cool skewed) of performance curve asymmetry does not strongly contribute to either persistence or lags. Conservation measures to support range-shifting populations may have most benefit near their environmental optimum or where the environmental dependence is shallow, irrespective of whether this is the leading or trailing edge. A metapopulation simulation corroborates our results. Our results shed fresh light on how key features of a species' environmental performance curve can impact its response to climate change.

AbstractCurrent anthropogenic environmental change causes rapid loss of biodiversity. Although the effects of the main causes of this loss (habitat fragmentation, climate change, and invasive species) on single species have been widely studied, the effects on species interactions are poorly understood. In particular, we do not yet understand how these phenomena affect the evolutionary processes that impact species interactions. Coevolution is a dominant process that organizes the web of life: most species are involved in at least one coevolved interaction. Due to rapid human modification of landscapes it is important to understand how subsequent changes in biotic and abiotic environment and in the level and distribution of genetic variation, as well as changes in population structures, influence the elements of the coevolutionary process. In this review, we synthesize recent development of theoretical work on the coevolution of interacting species with conservation genetics and the impact of anthropogenic environmental changes on single species to address the potential effects of habitat fragmentation, climate change, and invasive species on plant‐herbivore coevolution.