Data Center Trends Toward Higher Ambient Inlet Temperatures and the Impact on Server Performance

2013 ◽  
Author(s):  
Aparna Vallury ◽  
Jason Matteson
Keyword(s):  
Best Practices ◽  
Data Center ◽  
Design Guidelines ◽  
Thermal Design ◽  
Ambient Conditions ◽  
Performance Impact ◽  
Worst Case ◽  
Inlet Conditions ◽  
It Efficiency ◽  
The Impact

With the extension of the 2011 ASHRAE Thermal Design Guidelines to incorporate a broader Class A3 and A4 specification, the server industry is trying to adapt to the changing landscape of industry best practices and initiatives, and adopt the new ASHRAE Class A3 and A4 environments. In order to accommodate the high ambient inlet conditions while meeting the IT efficiency initiatives in the industry, certain design considerations must occur and it becomes very important to understand the implication of adhering to Class A3 and A4 environments on the performance of the servers. This paper describes a study that was conducted to understand the impact on performance of different servers under various workloads and inlet ambient conditions specifically adhering to class A3 specification only. The results from the study are presented in this paper which shows that no performance impact was observed in a 35°C environment, and bounded by 2% running worst case applications at 40°C and 0% when running lighter loads.

Comparative Analysis of Different In Row Cooler Management Configurations in a Hybrid Cooling Data Center

2015 ◽  
Author(s):  
Tianyi Gao ◽  
Bahgat G. Sammakia ◽  
James Geer ◽  
Bruce Murray ◽  
Russell Tipton ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Data Center ◽  
Power Plants ◽  
Data Centers ◽  
Electricity Consumption ◽  
Design Guidelines ◽  
Cooling Systems ◽  
Density Data ◽  
Hybrid Cooling ◽  
The Impact

The heat dissipated by electronic equipment inside data centers is increasing at a rapid rate due to the increasing of performance requirement and package density. This ever increasing power leads to critical challenges of thermal management for these high power density data centers. Energy consumption is also a key issue for high density data centers. Roughly 1.5% of all U.S. electricity consumption in the year 2006 was related to data centers, while that number increased to 2% by the year 2010. In 2013, U.S. data centers consumed approximately 91 billion kilowatt-hours of electricity. This amount of the electricity equals the annual output of 34 500-megawatt coal-fired power plants [1]. Cooling systems constitute a significant portion of the energy consumption of data centers, being approximately 25%∼35% of the total energy usage. Therefore, there is a large potential to save energy by optimizing current existing cooling systems and investigating new cooling technologies, and, at the same time, improving the overall cooling capacity and efficiency. This paper describes and investigates a hybrid cooling technology which utilizes in row coolers in existing raised floor air cooled data centers. The in row cooler functions as a liquid-to-air heat exchanger. In addition to the traditional raised floor cold aisle-hot aisle arrangements, the in row cooler is installed between the IT equipment to enable delivering the liquid coolant medium closer to the IT equipment. The in row coolers intake the hot air from the hot aisle, condition it, and supply the chilled air to the cold aisle. Thus, by extracting a large portion of the heat more directly into the cooling liquid through the in row coolers compared with the perimeter CRAH unit, the overall cooling performance and efficiency can potentially be improved. CFD models for an in row cooler and a representative data center room are developed. Experimentally characterized performance data are used to calibrate and validate the models. The models are then used to conduct a detailed computational analysis to assess the effectiveness of different arrangement configurations of in row cooler units in two rows of racks along one cold aisle. The detailed performance of the entire cold aisle is characterized using the rack inlet air temperature and a temperature nonuniformity factor. The impact of CRAH location and room layout are also investigated. This study is based on a practical problem and the corresponding results and analysis provide basic installation and design guidelines for future equipment upgrading in certain parts of the data center.

Impact of Predicted Combustor Outlet Conditions on the Aerothermal Performance of Film-Cooled HPT Vanes

2018 ◽  
Author(s):  
S. Cubeda ◽  
L. Mazzei ◽  
T. Bacci ◽  
A. Andreini
Keyword(s):  
Cooling System ◽  
Thermal Design ◽  
Temperature Fields ◽  
Thermal Loads ◽  
Rans Model ◽  
Numerical Predictions ◽  
Safety Margins ◽  
Rans Models ◽  
Inlet Conditions ◽  
The Impact

Turbine inlet conditions in modern aero-engines employing lean-burn combustors are characterised by highly swirled flow and non-uniform temperature distributions. As a consequence of the lack of confidence in numerical predictions and the uncertainty of measurement campaigns, the use of wide safety margins is of common practice in the design of turbine cooling systems, thus affecting the engine performance and efficiency. Previous experiences showed how only scale-resolving approaches such as Large-eddy and Scale-adapting simulations are capable of overcoming the limitations of RANS, significantly improving the accuracy in the prediction of flow and temperature fields at the combustor outlet. However it is worth investigating the impact of such differences on the aerothermal performance of the NGVs, as to understand the limitations entailed in the current approach for their thermal design. Industrial applications in fact usually rely on 1D, circumferentially-averaged profiles of pressure, velocity and temperature at the combustor-turbine interface in conjunction with Reynolds-averaged Navier-Stokes (RANS) models. This paper describes the investigation performed on an experimental test case consisting of a combustor simulator equipped with NGVs. Three numerical modelling strategies were compared in terms of flow field and thermal loads on the film-cooled vanes: i) RANS model of the NGVs with inlet conditions obtained from a RANS simulation of the combustor; ii) RANS model of the NGVs with inlet conditions obtained from a Scale-Adaptive Simulation (SAS) of the combustor; iii) SAS model inclusive of both combustor and NGVs. The results of this study show that estimating the aerodynamics at the NGV exit does not demand particularly complex approaches, whereas the limitations of standard RANS models are highlighted again when the turbulent mixing is key. High-fidelity predictions of the conditions at the turbine entrance proved to be very beneficial to reduce discrepancies in the estimation of local adiabatic wall temperature of even 100 K. However, a further leap forward can be achieved with an integrated simulation, capable of reproducing the transport of the unsteady fluctuations generated in the combustor up into the turbine, which plays a key role in presence of film cooling. This work therefore points out how keeping the analysis of combustor and NGVs separate can lead to a significantly misleading estimation of the thermal loads and ultimately to a wrong thermal design of the cooling system.

Impact of Predicted Combustor Outlet Conditions on the Aerothermal Performance of Film-Cooled High Pressure Turbine Vanes

2018 ◽  
Vol 141 (5) ◽  
Author(s):  
S. Cubeda ◽  
L. Mazzei ◽  
T. Bacci ◽  
A. Andreini
Keyword(s):  
Film Cooling ◽  
Cooling System ◽  
Engine Performance ◽  
Thermal Design ◽  
Separate Analysis ◽  
Lean Burn ◽  
Rans Model ◽  
Temperature Distributions ◽  
Inlet Conditions ◽  
The Impact

Turbine inlet conditions in lean-burn aeroengine combustors are highly swirled and present nonuniform temperature distributions. Uncertainty and lack of confidence associated with combustor-turbine interaction affect significantly engine performance and efficiency. It is well known that only Large-eddy and scale-adaptive simulations (SAS) can overcome the limitations of Reynolds-averaged Navier–Stokes (RANS) in predicting the combustor outlet conditions. However, it is worth investigating the impact of such improvements on the predicted aerothermal performance of the nozzle guide vanes (NGVs), usually studied with RANS-generated boundary conditions. Three numerical modelling strategies were used to investigate a combustor-turbine module designed within the EU Project FACTOR: (i) RANS model of the NGVs with RANS-generated inlet conditions; (ii) RANS model of the NGVs with scale-adaptive simulation (SAS)-generated inlet conditions; (iii) SAS model inclusive of both combustor and NGVs. It was shown that estimating the aerodynamics through the NGVs does not demand particularly complex approaches, in contrast to situations where turbulent mixing is key. High-fidelity predictions of the turbine entrance conditions proved very beneficial to reduce the discrepancies in the estimation of adiabatic temperature distributions. However, a further leap forward can be achieved with an integrated simulation, capable of reproducing the transport of unsteady fluctuations generated from the combustor through the turbine, which play a key role in presence of film cooling. This work, therefore, shows how separate analysis of combustor and NGVs can lead to a poor estimation of the thermal loads and ultimately to a wrong thermal design of the cooling system.

Optimising pig welfare during transport, lairage and slaughter

2021 ◽  
pp. 247-278
Author(s):  
Luigi Faucitano ◽  
◽  
Antonio Velarde ◽  
Keyword(s):  
Best Practices ◽  
Meat Quality ◽  
Physiological Response ◽  
Economic Losses ◽  
Ambient Conditions ◽  
Pork Industry ◽  
Research Findings ◽  
The Impact

Preslaughter practices, such as transport, handling and slaughter, can affect the welfare of pigs, and carcass and meat quality both individually and additively. Poor transport conditions and handling may result in loss of profits due to animal losses, carcass downgrading and meat quality defects. These economic losses are limited when the design of trucks is improved, the recommended transport, handling, stunning and slaughter practices are applied and the ambient conditions are controlled. The objective of this chapter is to overview research findings on the effects of transport, handling and slaughter practices on behavioral and physiological response, and carcass and meat quality in pigs, and to provide recommendations about the best practices aimed at limiting the impact of these factors on the pork industry economy.

From Chip to Cooling Tower Data Center Modeling: Influence of Server Inlet Temperature and Temperature Rise Across Cabinet

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Thomas J. Breen ◽  
Ed J. Walsh ◽  
Jeff Punch ◽  
Amip J. Shah ◽  
Cullen E. Bash
Keyword(s):  
Heat Flow ◽  
Temperature Rise ◽  
Data Center ◽  
Cooling Tower ◽  
Thermal Design ◽  
Inlet Temperature ◽  
Efficient System ◽  
Current Strategy ◽  
Data Center Cooling ◽  
The Impact

To achieve reductions in the power consumption of the data center cooling infrastructure, the current strategy in data center design is to increase the inlet temperature to the rack, while the current strategy for energy-efficient system thermal design is to allow increased temperature rise across the rack. Either strategy, or a combination of both, intuitively provides enhancements in the coefficient of performance of the data center in terms of computing energy usage relative to cooling energy consumption. However, this strategy is currently more of an empirically based approach from practical experience, rather than a result of a good understanding of how the impact of varying temperatures and flow rates at rack level influences each component in the chain from the chip level to the cooling tower. The aim of this paper is to provide a model to represent the physics of this strategy by developing a modeling tool that represents the heat flow from the rack level to the cooling tower for an air cooled data center with chillers. This model presents the performance of a complete data center cooling system infrastructure. After detailing the model, two parametric studies are presented that illustrate the influence of increasing rack inlet air temperature, and temperature rise across the rack, on different components in the data center cooling architecture. By considering the total data center, and each component’s influence on the greater infrastructure, it is possible to identify the components that contribute most to the resulting inefficiencies in the heat flow from chip to cooling tower and thereby identify the components in need of possible redesign. For the data center model considered here it is shown that the strategy of increasing temperature rise across the rack may be a better strategy than increasing inlet temperature to the rack.

Strategic Audit Inquiry: The Impact of Timing and the Promotion of Statutory Protections on Client Fraud Disclosures

2020 ◽  
Vol 34 (3) ◽  
pp. 153-167
Author(s):  
John R. Lauck ◽  
Stephen J. Perreault ◽  
Joseph R. Rakestraw ◽  
James S. Wainberg
Keyword(s):  
Best Practices ◽  
Audit Quality ◽  
Self Regulation ◽  
Data Availability ◽  
Audit Committees ◽  
External Auditors ◽  
Extant Literature ◽  
Psychological Theories ◽  
Inquiry Process ◽  
The Impact

SYNOPSIS Auditing standards require external auditors to inquire of client-employees regarding their knowledge of actual or suspected fraud (PCAOB 2010b; AICPA 2016). However, the extant literature provides little guidance on practical methods that auditors can employ to increase the likelihood of fraud disclosure and improve audit quality. Drawing upon best practices in the whistleblowing literature and psychological theories on self-regulation, we experimentally test the efficacy of two practical strategies that auditors can employ during the fraud inquiry process: actively promoting statutory whistleblower protections and strategically timing their fraud inquiries. Our results indicate that auditors are more likely to elicit client-employee fraud disclosures by actively promoting statutory whistleblower protections and strategically timing the fraud inquiry to take place in the afternoon, when client-employee self-regulation is more likely to be depleted. These two audit inquiry strategies should be of considerable interest to audit practitioners, audit committees, and those concerned with improving audit quality. Data Availability: From the authors by request.

scholarly journals HTPC: heterogeneous traffic-aware partition coding for random packet spraying in data center networks

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiawei Huang ◽  
Shiqi Wang ◽  
Shuping Li ◽  
Shaojun Zou ◽  
Jinbin Hu ◽  
...  
Keyword(s):  
Data Center ◽  
Large Scale ◽  
Network Performance ◽  
Rooted Tree ◽  
Heterogeneous Traffic ◽  
Data Center Networks ◽  
Packet Reordering ◽  
Traffic Characteristics ◽  
Network Utilization ◽  
The Impact

AbstractModern data center networks typically adopt multi-rooted tree topologies such leaf-spine and fat-tree to provide high bisection bandwidth. Load balancing is critical to achieve low latency and high throughput. Although the per-packet schemes such as Random Packet Spraying (RPS) can achieve high network utilization and near-optimal tail latency in symmetric topologies, they are prone to cause significant packet reordering and degrade the network performance. Moreover, some coding-based schemes are proposed to alleviate the problem of packet reordering and loss. Unfortunately, these schemes ignore the traffic characteristics of data center network and cannot achieve good network performance. In this paper, we propose a Heterogeneous Traffic-aware Partition Coding named HTPC to eliminate the impact of packet reordering and improve the performance of short and long flows. HTPC smoothly adjusts the number of redundant packets based on the multi-path congestion information and the traffic characteristics so that the tailing probability of short flows and the timeout probability of long flows can be reduced. Through a series of large-scale NS2 simulations, we demonstrate that HTPC reduces average flow completion time by up to 60% compared with the state-of-the-art mechanisms.

scholarly journals Improving the usability of climate indicator visualizations through diagnostic design principles

2021 ◽  
Vol 166 (3-4) ◽  
Author(s):  
Michael D. Gerst ◽  
Melissa A. Kenney ◽  
Irina Feygina
Keyword(s):  
Design Guidelines ◽  
Party Affiliation ◽  
Abstract Concepts ◽  
Design Modification ◽  
Climate Indicators ◽  
Present Complex ◽  
Control Versus ◽  
Climate Indicator ◽  
Political Party Affiliation ◽  
The Impact

AbstractVisual climate indicators have become a popular way to communicate trends in important climate phenomena. Producing accessible visualizations for a general audience is challenging, especially when many are based on graphics designed for scientists, present complex and abstract concepts, and utilize suboptimal design choices. This study tests whether diagnostic visualization guidelines can be used to identify communication shortcomings for climate indicators and to specify effective design modifications. Design guidelines were used to diagnose problems in three hard-to-understand indicators, and to create three improved modifications per indicator. Using online surveys, the efficacy of the modifications was tested in a control versus treatment setup that measured the degree to which respondents understood, found accessible, liked, and trusted the graphics. Furthermore, we assessed whether respondents’ numeracy, climate attitudes, and political party affiliation affected the impact of design improvements. Results showed that simplifying modifications had a large positive effect on understanding, ease of understanding, and liking, but not trust. Better designs improved understanding similarly for people with different degrees of numerical capacity. Moreover, while climate skepticism was associated with less positive subjective responses and greater mistrust toward climate communication, design modification improved understanding equally for people across the climate attitude and ideological spectrum. These findings point to diagnostic design guidelines as a useful tool for creating more accessible, engaging climate graphics for the public.

Data and visual displays in the Journal of Ecology 1996–2016

2020 ◽  
pp. 147387162098012
Author(s):  
Alon Friedman
Keyword(s):  
Best Practices ◽  
Pearson Correlation ◽  
Single Species ◽  
Data Type ◽  
Reliability Test ◽  
Visual Displays ◽  
Domain Type ◽  
Academic Publications ◽  
The Creation ◽  
The Impact

Scholars in scientific disciplines face unique challenges in the creation of visualizations, especially in publications that require insights derived from analyses to be visually displayed. The literature on visualizations describes different techniques and best practices for the creation of graphs. However, these techniques have not been used to evaluate the impact of visualizations in academic publications. In the field of ecology, as in other scientific fields, graphs are an essential part of journal articles. Little is known about the connections between the kind of data presented and domain in which the researchers conducted their study that together produces the visual graphics. This study focused on articles published in the Journal of Ecology between 1996 and 2016 to explore possible connections between data type, domain, and visualization type. Specifically, this study asked three questions: How many of the graphics published between 1996 and 2016 follow a particular set of recommendations for best practices? What can Pearson correlations reveal about the relationships between type of data, domain of study, and visual displays? Can the findings be examined through an inter-reliability test lens? Out of the 20,080 visualizations assessed, 54% included unnecessary graphical elements in the early part of the study (1996–2010). The most common type of data was univariate (35%) and it was often displayed using line graphs. Twenty-one percent of the articles in the period studied could be categorized under the domain type “single species.” Pearson correlation analysis showed that data type and domain type was positively correlated ( r = 0.08; p ≤ 0.05). Cohen’s kappa for the reliability test was 0.86, suggesting good agreement between the two categories. This study provides evidence that data type and domain types are equally important in determining the type of visualizations found in scientific journals.

scholarly journals Reducing environmental impacts from garments through best practice garment use and care, using the example of a Merino wool sweater

2021 ◽  
Author(s):  
Stephen G. Wiedemann ◽  
Leo Biggs ◽  
Quan V. Nguyen ◽  
Simon J. Clarke ◽  
Kirsi Laitala ◽  
...  
Keyword(s):  
Environmental Impacts ◽  
Energy Demand ◽  
Best Practice ◽  
Western Europe ◽  
Impact Category ◽  
Fashion Industry ◽  
Worst Case ◽  
Multiple Users ◽  
Washing Machines ◽  
The Impact

Abstract Purpose Garment production and use generate substantial environmental impacts, and the care and use are key determinants of cradle-to-grave impacts. The present study investigated the potential to reduce environmental impacts by applying best practices for garment care combined with increased garment use. A wool sweater is used as an example because wool garments have particular attributes that favour reduced environmental impacts in the use phase. Methods A cradle-to-grave life cycle assessment (LCA) was used to compare six plausible best and worst-case practice scenarios for use and care of a wool sweater, relative to current practices. These focussed on options available to consumers to reduce impacts, including reduced washing frequency, use of more efficient washing machines, reduced use of machine clothing dryers, garment reuse by multiple users, and increasing number of garment wears before disposal. A sixth scenario combined all options. Worst practices took the worst plausible alternative for each option investigated. Impacts were reported per wear in Western Europe for climate change, fossil energy demand, water stress and freshwater consumption. Results and discussion Washing less frequently reduced impacts by between 4 and 20%, while using more efficient washing machines at capacity reduced impacts by 1 to 6%, depending on the impact category. Reduced use of machine dryer reduced impacts by < 5% across all indicators. Reusing garments by multiple users increased life span and reduced impacts by 25–28% across all indicators. Increasing wears from 109 to 400 per garment lifespan had the largest effect, decreasing impacts by 60% to 68% depending on the impact category. Best practice care, where garment use was maximised and care practices focussed on the minimum practical requirements, resulted in a ~ 75% reduction in impacts across all indicators. Unsurprisingly, worst-case scenarios increased impacts dramatically: using the garment once before disposal increased GHG impacts over 100 times. Conclusions Wool sweaters have potential for long life and low environmental impact in use, but there are substantial differences between the best, current and worst-case scenarios. Detailed information about garment care and lifespans is needed to understand and reduce environmental impacts. Opportunities exist for consumers to rapidly and dramatically reduce these impacts. The fashion industry can facilitate this through garment design and marketing that promotes and enables long wear life and minimal care.

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