Equipment Cabinets Research Articles

Sub-ambient daytime cooling effects and cooling energy efficiency of a passive sub-ambient daytime radiative cooling coating applied to telecommunication base stations— Part 1: Distributed base stations and long-lasting self-cleaning properties

To overcome the issue of overheating and conserve cooling energy consumption, a superamphiphobic passive sub-ambient daytime radiative cooling (PSDRC) coating was extensively applied to distributed telecommunication base stations. The top surfaces of the battery and equipment cabinets coated with the PSDRC coating indicated prominent sub-ambient cooling effects regardless of the climate; this resulted in substantially lower surface temperatures compared with their counterparts. The applications of the PSDRC coating reduced the chamber interior temperature of an equipment cabinet by 10.4 °C during noon hours and by 6.0 °C before sunrise. The PSDRC-coated base stations could properly operate without air conditioners by replacing the closed door with a modified one containing an external exhaust system. The drastic decrease in the chamber interior temperature of the PSDRC base stations allowed them to conserve a considerable amount of cooling energy; this, resulted in cooling energy efficiencies between 31.7% and 64.9%. After more than one year, the surfaces of the PSDRC base station near busy city transit roads were still spotless and super non-wettable; this demonstrated the significance of the superamphiphobic self-cleaning topcoat and provided the top surfaces of the base stations in various regions with identical sub-ambient cooling effects on the initial state.

Development of risk mitigation guidance for sensor placement inside mechanically ventilated enclosures – Phase 1

Guidance on Sensor Placement was identified as the top research priority for hydrogen sensors at the 2018 HySafe Research Priority Workshop on hydrogen safety in the category Mitigation, Sensors, Hazard Prevention, and Risk Reduction. This paper discusses the initial steps (Phase 1) to develop such guidance for mechanically ventilated enclosures. This work was initiated as an international collaborative effort to respond to emerging market needs related to the design and deployment equipment for hydrogen infrastructure that is often installed in individual equipment cabinets or ventilated enclosures. The ultimate objective of this effort is to develop guidance for an optimal sensor placement such that, when integrated into a facility design and operation, will allow earlier detection at lower levels of incipient leaks, leading to significant hazard reduction. Reliable and consistent early warning of hydrogen leaks will allow for the risk mitigation by reducing or even eliminating the probability of escalation of small leaks into large and uncontrolled events. To address this issue, a study of a real-world mechanically ventilated enclosure containing GH2 equipment was conducted, where CFD modeling of the hydrogen dispersion (performed by AVT and UQTR, and independently by the JRC) was validated by the NREL Sensor laboratory using a Hydrogen Wide Area Monitor (HyWAM) consisting of a 10-point gas and temperature measurement analyzer. In the release test, helium was used as a hydrogen surrogate. Expansion of indoor releases to other larger facilities (including parking structures, vehicle maintenance facilities and potentially tunnels) and incorporation into QRA tools, such as HyRAM is planned for Phase 2. It is anticipated that results of this work will be used to inform national and international standards such as NFPA 2 Hydrogen Technologies Code, Canadian Hydrogen Installation Code (CHIC) and relevant ISO/TC 197 and CEN documents.

Profitable areas in large-scale FTTH network optimization

We present an optimization platform for Fiber-to-the-Home network design. The platform is capable of minimizing the capital expenditures (CAPEX) of network deployment by optimizing locations of optical equipment, signal splitters and cable cabinets, optimizing cable routes and types of cables as well as the number and types of optical cards and splitters. We present the architecture of the platform, the design process it implements, and the algorithms it deploys. The platform is used to indicate the parts of the design process that require complex optimization with dedicated algorithms and those that can be left to appropriately crafted engineering rules. We indicate that while keeping the computation time acceptable, much of the CAPEX savings can be obtained when locations of optical equipment are thoroughly optimized, cable routes are determined with plain engineering rules, and finally, signal splitting patterns are optimized carefully to lower the fiber count and thus the cost of cables.

The Complications of Colocation: What the Federal Communication’s Rule Making May Mean for Your Community

You did it. You successfully worked with a wireless service provider to find the ideal spot for its new wireless tower. The tower is positioned perfectly—in the heart of downtown, yet safe, hidden, completely undisruptive. The provider is happy. The community is content. It’s a win‐win. Fast forward a month. The provider is back with a new idea: To support the latest technology and to enhance its revenues, it will add not one, but four 20‐foot extensions for new antennas. The extensions would make the otherwise hidden facility visible. They would reach across and over the sidewalk and street, presenting safety risks. And the provider would also add four new equipment cabinets and an equipment shelter. Your answer is easy: Absolutely not. We can find a better solution. But this time the provider is not asking, it’s demanding. It says that because it is not proposing an initial facility but a colocation, you must approve its requests. Whether the provider is correct may turn on how the Federal Communications Commission (FCC) resolves a pending rule making. This article describes the proceeding, key issues it raises, and what the proceeding may mean to you and your community. As a planner, you can influence the proceeding by meeting with the FCC to discuss the proposed rules and by responding to industry claims that local requirements are delaying deployment.

A simplified model for nonlinear seismic response analysis of equipment cabinets in nuclear power plants

An analytical model is required when the analysis method or the combined analysis and modal testing method is used as an aid to the seismic qualification (SQ) of equipment cabinets within nuclear power industry. This study proposes a simplified and computationally efficient model to represent the nonlinear dynamic behavior of the cabinet during earthquake. The presented model accounts for the softening behavior of the cabinets by incorporating the Duffing's type of restoring force. The characteristic of nonlinear restoring force for the finite element model (FEM) is based on the relationship of stress–strain of the element. Experiments have also been performed on an actual cabinet of nuclear power plant (NPP) to validate the model. The softening or reduction in dynamic stiffness of cabinets with increase in the excitation levels is observed in the experiments. It is also found that material yielding is not a significant source of the nonlinear behavior of the cabinet. The results obtained from the analysis using the proposed model are found to be in good agreement with the experimental results. The proposed model is expected to be useful for the prediction of seismic behavior of cabinets, particularly during the operation, owing to less computational effort required, accurate prediction of softening and no requirement of tests.

Editorial

Recently my colleague Dr Colin Fowler, of Aston University, gave me a copy of The Ophthalmic Optician dated 5th October 1968. He thought I would be interested as the picture on the cover of this issue showed the contact lens teaching clinics at Aston at that time (see Fig. 1). The clinics were almost unrecognisable from the current contact lens teaching clinics at Aston. The furnishings, the equipment cabinets, the consulting chairs – in fact even the location of the clinics were all different (since 1987 Optometry has been housed in a separate building away from the main buildings of Aston University).

Remembering Bruce Merrifield

Remembering Bruce Merrifield

Management of Increased Incidence of Clostridium Difficile Associated Diarrhea in a 90 Bed VA Nursing Home

BACKGROUND/OBJECTIVES: Incidence of Clostridium difficile associated diarrhea (CDAD) increased in a 90 bed nursing home from 1 per 100 patients(3/277) in the first quarter to 2.4 per 100 patients(6/222) in the second quarter FY04. Immediate actions included (1) Reinforcing staff hand washing with soap and water rather than waterless 62.5% ethyl alcohol hand rub for patients with undiagnosed diarrhea, (2) Changing hospital disinfectant to sodium hypochlorite solution, (3) Placing patients with undiagnosed diarrhea empirically in Contact Precautions, and (4) Increasing frequency of laboratory performance of C. difficile toxins from 3 to 7 times weekly. Rates continued to increase in the 3 rd QTR FY04 to 3.4 per 100 cases (7/233). In response, leadership appointed a Root Cause Analysis (RCA) team to analyze the problem with the objective to reduce and control the incidence of CDAD. METHODS: The RCA composed of infection control, housekeeping, nursing, medicine, pharmacy, and supply evaluated the outbreak. Recommendations included: (1) Development of CDAD medical treatment algorithm, (2) Simplification of Contact Precaution signs highlighting importance of hand washing. (3) Extensive C. difficile education for all healthcare professionals, (5) Replacement of isolation carts with Personal Protective Equipment (PPE) cabinets to improve PPE availability, and (6) Improved tracking of CDAD patients transferred in the facility to ensure continuation of precautions. Cost analysis was conducted for CDAD cases vs. non CDAD cases. Fisher's exact was applied to determine association of incidence before and after actions. RESULTS: Recommendations were implemented in the 4 th QTR FY04. Cases peaked at 4.4 per 100 patients (10/226). (p CONCLUSIONS: Management and education significantly impacted CDAD occurrence as evidenced by the decrease and control of incidence. Significant cost savings at an estimated $1,395,000 were realized with CDAD prevention activities.

Modal Testing and Finite Element Analysis of a Battery Rack for Seismic Applications

One of the most challenging aspects of reliability testing in the telecommunication industry is earthquake resistance testing. Cabinet systems, battery racks, equipment racks, and distribution frames are considered compliant with Network Equipment-Building System (NEBSTM) criteria for surviving earthquake conditions if test results indicate (1) the maximum deflection of the top of the structure does not exceed 7.6 cm (3 in.), (2) there are no permanent deformations or structural damage, and (3) the equipment or batteries remain functional (as defined in NEBS Requirements: Physical Protection, Specification GR-73 Issue 2). Based on seismic test results of a large population of telecom enclosures, it is accepted that a system always passes the seismic test if its fundamental natural frequency is at least 6 Hz. It is costly to produce and configure enclosures and conduct seismic qualification testing. To minimize the risk of telecom system failure, a modal finite element analysis (FEA) of the system should first be performed. Numerical results of the FEA should then be verified with experimental resonance search data generated by modal testing or sine sweep testing, combined with static pull testing where applicable. The resonance search results will determine the need for seismic testing (seismic analysis) prior to seismic qualification testing. This paper elaborates on key aspects of the static pull test method supported by the test results for a cabinet framework and a configured cabinet relative to the seismic test results. The paper also discusses sine sweep testing of a battery cabinet and results of two modal test methods used on the corresponding battery rack. Finally, this paper describes modal FEA of the same battery rack anchored to a concrete pad supported by a polystyrene plastic foam sheet and explains the correlation of the numerical results with the experimental modal analysis results. The correlated model serves as the baseline model for analyzing other battery racks and equipment cabinets configured with batteries.

The use of digital filtering techniques for the simulation of fine features in emc problems solved in the time domain

In this paper, the development and implementation of digital filters for the incorporation of fine features in time-domain electromagnetic codes is described. Examples are shown for the shielding effectiveness of equipment cabinets with perforated walls with/without printed circuit boards inside. Comparisons with measurements show excellent agreement. This approach results in substantial savings in computational storage, memory and in problem definition. Results were obtained by combining this technique with the transmission-line modeling method, but it can also be used in conjunction with other methods to simulate complex electromagnetic compatibility problems.

Application of a semi-empirical approach to the thermal design of electronic equipment

A semi-empirical approach to the thermal design of electronic equipment is presented. Although recent progress in computer technology has enabled a complex analysis to be made, it is difficult to carry out numerical studies for practical electronic equipment cabinets, which have extremely complicated boundary conditions due to the various sized components mounted in the cabinets. It has thus become important to establish an analytical model in order to apply computer simulation to the thermal design of electronic equipment. This paper reports the semi-empirical approach based on a lumped model, and experimental data on the flow resistance coefficient and heat transfer coefficient. A simulation was carried out for a photocopy machine model by using a personal computer. The proposed method is confirmed to be capable of serving thermal designers satisfactorily.

Shielding effectiveness of single and double plates with slits

Transverse electric (TE) wave transmission through slits on single and double metal plates of finite thickness is studied by using Galerkin's method. It is observed that by either using a thick plate (for slit narrower than half a wavelength) or using double plates with slits laterally shifted (for slits wider than half a wavelength), the amount of power transmitted through the slits can be significantly reduced. These schemes can be applied to improve the shielding effectiveness of equipment cabinets.

On the Cooling of Natural-air-cooled Electronic Equipment Casings : Proposal of a Practical Formula for Thermal Design

This paper presents a simple formula for thermal designing of natural-air-cooled electronic equipment casings with standard arrangement of circuit boards and power supplies. The formula meets the requirements as a practical formula, since it represents an air-cooling system in its simplified form with due regard to such factors as the stack effect, air flow resistance, natural convective transfer and so on. The formula was applied to predict the temperature rise in two practically used electronic equipment cabinets with standard arrangements and a modeling case. The predicted temperature rise values, obtained through the formula, slightly differed - within 10 percent - from the actual values based upon experiment results.

Aeromedical Transport of the Seriously Ill Patient

Most of us are aware of the medical airlifts that were practiced by the United States Air Force during the Korean and Viet Nam conflicts. Likewise, we read regularly of the air transport of one or more severely burned patients from the scene of an accident to the Burn Center at Brooke Army Medical Center in San Antonio, Texas. But what is not generally known is the daily movement of patients who are armed forces members, or their dependents, throughout the world for the purpose of receiving sophisticated medical care, regardless of where they may be stationed.The reasons for this service are two: first, quite obviously, it is humanitarian; second, it is a way for the Air Force to maintain medical readiness for their wartime mission by exercising this system on a daily basis during peacetime. We are talking about a worldwide network whose major and minor branches sweep around the globe.Patients are air transported according to three levels of need: routine, high priority, and urgent. This article will be limited to a general description of the necessary hardware and current practices used for the urgent mission.We use three types of aircraft: the Huey helicopter for short distances; the C-9, a two-engined jet, for medium range; and the C-141, a four-engined jet, for intercontinental transport. The medical modifications to the C-9 include a built-in ramp; a nurses' station similar to that found on a hospital ward, complete with built-in drug and equipment cabinets; multiple sources for oxygen and suction; and ready communication fore and aft. Seats can be quickly removed, leaving space for litters in tiers, infant isolettes and Stryker frames.

On the cooling of natural-air-cooled electronic equipment casings (Proposal of a practical formula for thermal design)

This paper presents a simple formula for thermal designing of natural-air-cooled electronic equipment casings with standard arrangement for circuit boards and power supplies. The formula meets the requirements as a practical formula, since it represents the air-cooling system in its simplified form with due regard to such factors as the stack effects, air Flow resistance, natural convective transfer and so on. The formula was applied to predict temperature rise for two practically used electronic equipment cabinets with standard arrangements and a modeling case. The predicted temperature rise values, obtained through the formula, caused very slight errors, with only 10 percent in the actual values based upon experiment results.