Radiative Cooling to the Night Sky

Silicon wafer fabrication facilities require a significant amount of temperate cooling water to meet high internal cooling loads. The tertiary chilled water systems operate year round to fulfil the constant cooling load needed for production. Conventional chillers require a large amount of electricity to cool the water by the vapor compression cycle. As energy costs increase and environmental stewardship becomes the norm in industry, sustainable technologies are needed to chill process cooling water without the significant energy consumption of today’s chillers. Night sky radiation cools a medium by radiating heat from a warm medium to the colder night sky. The Intel silicon wafer manufacturing facility in Rio Rancho, New Mexico was selected to be an ideal location for the implementation of two full-scale designs. Numerous system designs were examined during a thorough literature survey, and an open water system was chosen as the best alternative because of its superior heat transfer ability and lower construction cost. At the suggestion of an external auditor, a closed system was studied further, designed, and economically analyzed. Recommendations for system choice are based on economic analyses, system operability, and environmental considerations. To aid in model construction and full-scale design, an extensive research program was developed to confirm literature correlations and determine the effectiveness of radiation to the night sky as a method used to cool water. Experiments that cooled an aluminum plate through the ambient temperature were used to confirm and verify the accuracy of Berdahl and Martin’s correlation for calculating the effective temperature of the night sky. A prototype for the open water system was built to demonstrate the cooling ability of the design. Operation of the prototype successfully demonstrated radiative night sky cooling, showed the benefit of convective heat transfer when the ambient air temperature is below the water temperature, and validated Berdahl and Martin’s model. With the experimental stage complete, the prototype system was scaled-up to a system for the Intel facility in Rio Rancho. The system diverts cooling water from Intel’s cooling water system into surge tanks. From the surge tanks, water is pumped up to the roof and is distributed among corrugated metal roofing units placed on top of the Intel central utilities building. The corrugated panels are supported by a pressure treated lumber frame. The chilled water isdistributed and collected by a PVC piping network. Model simulations of the full-scale system determined the cooling capability of the system. The full-scale simulation predicted that the system would eliminate over 90% of the night-time chiller cooling loads during the winter. Throughout the year, the chillers use $280,000 worth of electricity1. The radiative cooling system will save the company$75,000 in annual electricity costs, a decrease in electricity consumption of 27%. The electricity generation portfolio of PNM, Intel’s electricity provider, was used to determine that the system will prevent approximately 930 tons of carbon dioxide from being released into the atmosphere. The reduction of produced electricity will also conserve 4,220,000 gallons of water, a scarce resource in the southwestern Unites States. For the open system, the total capital cost is $353,500 and the operating cost, including electricity to operate the unit, is$31,600/year. For the closed system, the total capital cost is $636,500 and the operating cost, including electricity to operate the unit, is$12,000/year. The average net reduction in annual electrical usage is 1,282 MW-hr and the average yearly electrical cost savings is $75,265 for both systems. The payback period for the open and closed systems are estimated to be 4.77 years and 6.8 years, respectively. The radiative cooling system will economically benefit the Intel facility; however, the reduction in carbon emissions and water usage is of immense importance to the public and a company as dedicated to environmental initiatives as is Intel

Climate and Surging of Donjek Glacier, Yukon, Canada

Links between climate and glacier surges are poorly understood but are required to enable prediction of surges and mitigation of associated hazards. Here, we investigate the role of snow accumulation, rain, and temperature on surge periodicity, area changes, and timing of surge initiation since the 1930s at Donjek Glacier, Yukon, Canada. Snow accumulation measured in three ice cores collected at Eclipse Icefield indicates that a cumulative accumulation of 15.5 ± 1.46 or 16.6 ± 2.0 m w.e. occurred in the ten to twelve years between each of its last eight surges, depending on ice motion spatiotemporal offset corrections. Although we find consistent snow accumulation between surges, the transient snow line has risen 10.3 m decade−1 vertically since the 1950s, and Burwash Landing weather station records indicate a 0.5°C decade−1 increase in mean annual air temperature since the 1960s. Changes in surface mass balance are accompanied by a consistent surge interval but decreasing surge extent. The three recent surge events initiated in years with the rainiest summers on record. These findings highlight a complex interplay between external (i.e., climate) and internal glacier processes that control surging at Donjek Glacier, with climate having a more direct influence on surge extent than on recurrence interval

A Constraint Solver for PHP Arrays

International audienceIn previous works, we have proposed Praspel, a framework for contract-based testing in PHP. Among others, it includes a specification language and a unit test generator which automatically generates test data from formal preconditions. The generator sometimes rejects data, when they do not satisfy parts of the preconditions. In many cases, generation with rejection is not efficient enough. Thus we investigate practical contexts where more efficient generation algorithms can be designed and we extend Praspel with their implementation. After strings, that we have already considered, the most frequent data type in PHP is arrays. They cover most of the needs for collections, because they can store key-value pairs of any kind, they do not have a specific length or depth, and they are efficiently implemented. In this paper, we report on a study to know what are the most popular constraints on PHP arrays. Then we formalize these constraints and we present an implementation in PHP of a constraint solver for these constraints. In this context, the constraint-based approach removes all the rejections

Analysis of Antarctic Peninsula Glacier Frontal Ablation Rates with Respect to Iceberg Melt-Inferred Variability in Ocean Conditions

Marine-terminating glaciers on the Antarctic Peninsula (AP) have retreated, accelerated and thinned in response to climate change in recent decades. Ocean warming has been implicated as a trigger for these changes in glacier dynamics, yet little data exist near glacier termini to assess the role of ocean warming here. We use remotely-sensed iceberg melt rates seaward of two glaciers on the eastern and six glaciers on the western AP from 2013 to 2019 to explore connections between variations in ocean conditions and glacier frontal ablation. We find iceberg melt rates follow regional ocean temperature variations, with the highest melt rates (mean ≈ 10 cm d−1) at Cadman and Widdowson glaciers in the west and the lowest melt rates (mean ≈ 0.5 cm d−1) at Crane Glacier in the east. Near-coincident glacier frontal ablation rates from 2014 to 2018 vary from ~450 m a−1 at Edgeworth and Blanchard glaciers to ~3000 m a−1 at Seller Glacier, former Wordie Ice Shelf tributary. Variations in iceberg melt rates and glacier frontal ablation rates are significantly positively correlated around the AP (Spearman\u27s ρ = 0.71, p-value = 0.003). We interpret this correlation as support for previous research suggesting submarine melting of glacier termini exerts control on glacier frontal dynamics around the AP

Praspel: Contract-Driven Testing for PHP using Realistic Domains

We present an integrated contract-based testing framework for PHP. It relies on a behavioral interface specification language called Praspel, for "PHP Realistic Annotation and Specification Language". Using Praspel developers can easily annotate their PHP scripts with formal contracts, namely class invariants, and method pre- and postconditions. These contracts describe assertions either by predicates or by assigning realistic domains to data. Realistic domains introduce types in PHP and describe complex structures frequently encountered in applications, such as email addresses or SQL queries. Realistic domains display two properties: predicability, which allows to check if a data belongs to a given realistic domain, and samplability, which allows to generate valid data. This paper introduces coverage criteria dedicated to contracts, designed to exhibit relevant behaviors of the annotated methods. Test data are then computed to satisfy these coverage criteria, by using dedicated data generators for complex realistic domains, such as arrays or strings. This framework has been implemented and disseminated within the PHP community, which gave us feedback on their usage of the tool and the relevance of this integrated process with respect to their practice of manual testing

Evaluation of IP-10 and TNFalpha-transducing parvoviral vectors as antitumoral agents in animal glioblastoma models

This work evaluated the efficacy of parvoviral vectors expressing human IP-10 or mouse TNFalpha as tools against subcutaneous glioblastoma tumors in two animal models. First, new recombinant MVMp- and H1- based vectors expressing human IP-10 or mouse TNFalpha were constructed. It was shown that parvoviral vectors could effectively infect both human and murine glioblastoma cells. High amounts of the transgene proteins were produced upon infection with particular vectors. All tested cell lines were sensitive to wild type parvoviruses. Two animal models were established: murine Gl261 glioma cells were used for inducing subcutaneous tumors in C57/Bl6 mice and human U87 glioblastoma cells produced subcutaneous tumors in cd1 swiss nude mice. The antitumoral effects mediated in vivo by recombinant and wild type parvoviruses (MVMp and H1) were investigated in these animal models. High efficacy of IP-10 and TNFalpha-encoding parvoviral vectors could be demonstrated in both models. Infecting tumor cells with recombinant parvoviruses encoding IP-10 or TNFalpha as well as treating established tumors with these vectors provided conditions to observe antitumor effect. In nude mice combined IP-10/TNFalpha expression resulted with significant tumor growth delay, reduced tumor volume and prolongation of animal survival. This effect was not dependent on angiogenesis inhibition. It is possible that NK cells participate in observed antitumoral effects. The best therapeutic effect – complete tumor eradication – could be demonstrated in immunocompetent animals. This effect was reached when both types of virus (IP-10 and TNFalpha-expressing) were administered simultaneously. Histological analysis and MRI study showed that antitumoral effects in this system (tumor growth delay, reduced tumor volume and prolongation of animal survival) were not dependent on the inhibition of angiogenesis. We were able to show that intact immune system is necessary to obtain a strong antitumor effect. Rechallenged animals are protected from tumor growth. Gl261 glioma cells can be specifically recognized by host spleenocytes. The data from the literature suggest that the main effectors in the antitumoral response could be CD8+ T cells. TNFalpha - expressing vector demonstrated the ability to support dendritic cell maturation. In the systems investigated here the effectiveness of wild type H1 and MVMp viruses could not be demonstrated. Taken together, the data obtained in this work are promising and suggest that recombinant parvoviruses are good candidates for gene therapy of glioma. In the future, antitumoral effects of these vectors should be investigated in the intracranial system like well-described Gl261 model

Génération automatique de tests unitaires avec Praspel, un langage de spécification pour PHP

The works presented in this memoir are about the validation of PHPprograms through a new specification language, along with its tools. These works follow three axes: specification language, automatic test data generation and automatic unit test generation. The first contribution is Praspel, a new specification language for PHP, based on the Design by Contract. Praspel specifies data with realistic domains, which are new structures allowing to validate and generate data. Based on a contract, we are able to perform Contract-based Testing, i.e.using contracts to automatically generate unit tests. The second contribution isabout test data generation. For booleans, integers and floating point numbers, auniform random generation is used. For arrays, a dedicated constraint solver has been implemented and used. For strings, a grammar description language along with an LL(⋆) compiler compiler and several algorithms for data generation are used. Finally, the object generation is supported. The third contribution defines contract coverage criteria. These latters provide test objectives. All these contributions are implemented and experimented into tools distributed to the PHP community.Les travaux présentés dans ce mémoire portent sur la validation de programmes PHP à travers un nouveau langage de spécification, accompagné de ses outils. Ces travaux s’articulent selon trois axes : langage de spécification, génération automatique de données de test et génération automatique de tests unitaires.La première contribution est Praspel, un nouveau langage de spécification pour PHP, basé sur la programmation par contrat. Praspel spécifie les données avec des domaines réalistes, qui sont des nouvelles structures permettant de valider etgénérer des données. À partir d’un contrat écrit en Praspel, nous pouvons faire du Contract-based Testing, c’est à dire exploiter les contrats pour générer automatiquement des tests unitaires. La deuxième contribution concerne la génération de données de test. Pour les booléens, les entiers et les réels, une génération aléatoire uniforme est employée. Pour les tableaux, un solveur de contraintes a été implémenté et utilisé. Pour les chaînes de caractères, un langage de description de grammaires avec un compilateur de compilateurs LL(⋆) et plusieurs algorithmes de génération de données sont employés. Enfin, la génération d’objets est traitée.La troisième contribution définit des critères de couverture sur les contrats.Ces derniers fournissent des objectifs de test. Toutes ces contributions ont été implémentées et expérimentées dans des outils distribués à la communauté PHP

Brief Communication: Is Vertical Shear in an Ice Shelf (Still) Negligible?

Vertical shear is recognized today as a key component of the stress balance of ice shelves. However, the first ice shelf models were built on the neglect of vertical shear. Partly due to its historical treatment, it remains common to discuss vertical shear as though it were still considered negligible in ice shelf models. Here, we offer a historical perspective on the changing treatment of vertical shear over time, and we emphasize the term\u27s non-negligibility in current ice shelf modeling. We illustrate our discussion in the simplest context of an analytic, isothermal, shallow-ice-shelf model

Dynamic Mass Loss from Greenland\u27s Marine-Terminating Peripheral Glaciers (1985–2018)

Global glacier mass balance decreased rapidly over the last two decades, exceeding mass loss from the Greenland and Antarctic Ice Sheets. In Greenland, peripheral glaciers and ice caps (GICs) cover only ~5% of Greenland\u27s area but contributed ~20% of the island\u27s ice mass loss between 2000 and 2018. Although Greenland GIC mass loss due to surface meltwater runoff has been estimated using atmospheric models, mass lost to changes in ice discharge into oceans (i.e., dynamic mass loss) remains unquantified. We use the flux gate method to estimate discharge from Greenland\u27s 585 marine-terminating peripheral glaciers between 1985 and 2018, and compute dynamic mass loss as the discharge anomaly relative to the 1985–98 period. Greenland GICs discharged between 2.94 ± 0.23 and 4.03 ± 0.23 Gt a−1 from 1985 to 1998, depending on the gap-filling method, and abruptly increased to 5.10 ± 0.21 Gt a−1 from 1999 to 2018. The resultant ~1–2 Gt a−1 dynamic mass loss was driven by synchronous widespread acceleration around Greenland. The mass loss came predominantly from the southeast region, which contains 39% of the glaciers. Although changes in discharge over time were small relative to surface mass-balance changes, our speed and discharge time series suggest these glaciers may quickly accelerate in response to changes in climate