Flammability tests for cellular plastics—Part I

Many tests have been employed to describe the behavior of cellular plastics when exposed to fire. In this, the first part of a two-part article, the author discusses the requirements of various small-, medium-, and large-scale tests. Union Carbide Corporation Note: Based on a paper titled “The Flammability Characteristics of Cellular Plastics” delivered by the author at the May 1967 Polymer Conference at Wayne State University and subsequently published in the September 1967 issue ofIndustrial & Engineering Chemistry, Product Research and Development.     

Low-pressure membrane integrity tests for drinking water treatment: A review

Low-pressure membrane systems, including microfiltration (MF) and ultrafiltration (UF) membranes, are being increasingly used in drinking water treatments due to their high level of pathogen removal. However, the pathogen will pass through the membrane and contaminate the product if the membrane integrity is compromised. Therefore, an effective on-line integrity monitoring method for MF and UF membrane systems is essential to guarantee the regulatory requirements for pathogen removal. A lot of works on low-pressure membrane integrity tests have been conducted by many researchers. This paper provides a literature review about different low-pressure membrane integrity monitoring methods for the drinking water treatment, including direct methods (pressure-based tests, acoustic sensor test, liquid porosimetry, etc.) and indirect methods (particle counting, particle monitoring, turbidity monitoring, surrogate challenge tests). Additionally, some information about the operation of membrane integrity tests is presented here. It can be realized from this review that it remains urgent to develop an alternative on-line detection technique for a quick, accurate, simple, continuous and relatively inexpensive evaluation of low-pressure membrane integrity. To better satisfy regulatory requirements for drinking water treatments, the characteristic of this ideal membrane integrity test is proposed at the end of this paper.     

From Ignition to Suppression,a Thermal View of Flammability Limits

Starting from the flammability diagram, a thermal theory is proposed to scale various critical concentrations in combustion. By an analogy between ignition and suppression, the flammability limits are extrapolated to minimum extinguishing concentrations. Thus the suppressibility of a fuel will be evaluated from its flammability, while the suppression capability of an agent will be evaluated using the cup-burner (CB) value. By setting up the thermal balance at extinguishing, the synergistic effect can also be explained by an adjustable flame temperature factor. This thermal mechanism will guide the future work on selecting new combinations of binary agents.     

Leading Lady: Monica Pidgeon,Editor of Architectural Design, 1946 to 1975

Peter Murray pays tribute to Monica Pidgeon (1913-2009). Editor of Architectural Design for almost three decades, Monica was responsible for establishing Architectural Design as the premier international architectural magazine. Murray highlights her immense contribution to architecture over the years, as well as evoking the experience of working for Monica as one of her ‘boys’, or technical editors. Copyright © 2010 John Wiley & Sons, Ltd.     

Metamaterial filters: A review

In this paper, a review on metamaterial filters is presented. Several filters based on resonant-type composite right/left-handed metamaterial transmission lines are revised. The different results presented show the application possibilities of such structures in the design of filters with different bandwidths and performances. Some results based on other approaches are also shown.     

Unexposed-face temperature criteria in fire resistance tests: A reappraisal

Fire resistance tests for barriers, e.g., walls or floor/ceiling assemblies, utilize unexposed-face temperature criteria as one of the means of determining whether the specimen passes the test. The purpose of a temperature limit on the unexposed face is to prevent fire propagation which might occur by igniting adjacent combustibles in the space not yet fire-involved. The actual criteria date to 1918, with only trivial changes have been made subsequently. Knowledge gained in the intervening decades allows a much more realistic assessment of the potential for ignition. The current literature has been reviewed and the results indicate that the criteria used is excessively conservative. A recommendation is made that 400 °C represents a conservative bound to experimental data on all materials which could see potential use in any facilities that are not dedicated to the storage of hazardous goods (the existing fire-resistance standards are not intended for the protection of hazardous-goods occupancies, in any case). The 400 °C is a fixed value and not a temperature-rise value. Under the existing system, the criteria were two-fold: a limit on the average temperature rise, and a limit on the single-point (worst case) temperature rise. Since the values traditionally used were excessively conservative, the higher single-point limit at least served the function of making the entire criterion somewhat less excessive. This will not be needed if a criterion value is adopted which is more consistent with valid experimental data. Thus, it is recommended that a 400 °C temperature limit be adopted, applicable to any thermocouple location, and that a second, average value not be utilized. The review also indicates that the technique for making the unexposed-face measurement, i.e., the thermocouple+pad assembly, is better conceived in the ISO 834 test, thus it is recommended that this same technique be adopted in ASTM E 119.     

Stainless steel in construction: A review of research, applications, challenges and opportunities

Stainless steel has unique properties which can be taken advantage of in a wide variety of applications in the construction industry. This paper reviews how research activities over the last 20 years have impacted the use of stainless steel in construction. Significant technological advances in materials processing have led to the development of duplex stainless steels with excellent mechanical properties; important progress has also been made in the improvement of surface finishes for architectural applications Structural research programmes across the world have laid the ground for the development of national and international specifications, codes and standards spanning both the design, fabrication and erection processes. Recommendations are made on research activities aimed at overcoming obstacles to the wider use of stainless steel in construction. New opportunities for stainless steel arising from the shift towards sustainable development are reviewed, including its use in nuclear containment structures, thin-walled cladding and composite floor systems.     

Urban ecosystem health assessment: A review

Due to the important role of cities for regional, national, and international economic development and the concurrent degradation of the urban environmental quality under rapid urbanization, a systematic diagnosis of urban ecosystem health for sustainable ecological management is urgently needed. This paper reviews the related research on urban ecosystem health assessment, beginning from the inception of urban ecosystem health concerns propelled by the development needs of urban ecosystems and the advances in ecosystem health research. Concepts, standards, indicators, models, and case studies are introduced and discussed. Urban ecosystem health considers the integration of ecological, economic, social and human health factors, and as such it is a value-driven concept which is strongly influenced by human perceptions. There is not an absolute urban ecosystem standard because of the uncertainty caused by the changing human needs, targets, and expectation of urban ecosystem over time; thus, suitable approaches are still needed to establish health standards of urban ecosystems. Several conceptual models and suitable indicator frameworks have been proposed to organize the multiple factors to represent comprehensively the health characteristics of an urban ecosystem, while certain mathematical methods have been applied to deal with the indicator information to get a clear assessment of the urban ecosystem health status. Instead of perceiving the urban ecosystem assessment as an instantaneous measurement of the health state, it is suggested to conceptualize the urban ecosystem health as a process, which impels us to focus more studies on the dynamic trends of health status and projecting possible development scenarios.     

Dynamic rock tests using split Hopkinson(Kolsky)bar system-A review

Dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems.Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more challenging than their static counterparts. Dynamic tests are usually conducted using the split Hopkinson bar or Kolsky bar systems, which include both split Hopkinson pressure bar(SHPB) and split Hopkinson tension bar(SHTB) systems. Signi fi cant progress has been made on the quanti fi cation of various rock dynamic properties, owing to the advances in the experimental techniques of SHPB system.This review aims to fully describe and critically assess the detailed procedures and principles of techniques for dynamic rock tests using split Hopkinson bars. The history and principles of SHPB are outlined,followed by the key loading techniques that are useful for dynamic rock tests with SHPB(i.e. pulse shaping, momentum-trap and multi-axial loading techniques). Various measurement techniques for rock tests in SHPB(i.e. X-ray micro computed tomography(CT), laser gap gauge(LGG), digital image correlation(DIC), Moiré method, caustics method, photoelastic coating method, dynamic infrared thermography) are then discussed. As the main objective of the review, various dynamic measurement techniques for rocks using SHPB are described, including dynamic rock strength measurements(i.e.dynamic compression, tension, bending and shear tests), dynamic fracture measurements(i.e. dynamic imitation and propagation fracture toughness, dynamic fracture energy and fracture velocity), and dynamic techniques for studying the in fl uences of temperature and pore water.     

Variable refrigerant flow systems: A review

This review study presents a detailed overview of the configurations of the outdoor and indoor units of a multi-split variable refrigerant flow (VRF) system, and its operations, applications, marketing and cost. Besides, a detailed review about the experimental and numerical studies associated with the VRF systems is provided. The aim is to put together all the diversified information about the VRF systems in a single source. According to detailed review, it is observed that the compressor frequency and the electronic expansion valve opening should be controlled simultaneously for the control strategies, and it is concluded that VRF system not only consumes less energy than the common air conditioning systems such as variable air volume, fan-coil plus fresh air under the same conditions, but also provides better indoor thermal comfort as long as it is operated in the individual control mode. It is found that even though the main drawback of the VRF system is the high initial cost compared to the common air conditioning systems, due to the energy saving potential of the VRF system, the estimated payback period of the VRF system compared to an air cooled chiller system in a generic commercial building could be about 1.5 year.     

Fire spread tests—A critique

Propagation is perhaps the most alarming characteristic of a fire. Rate of advance is an extremely important factor in determining the likelihood of escape from a burning building and the ability of fire protection systems to protect property.     

Steel foam for structures: A review of applications,manufacturing and material properties

The objective of this paper is to provide a state-of-the-art review for the structural application, manufacturing, material properties, and modeling of a new material: steel foam. Foamed steel includes air voids in the material microstructure and as a result introduces density as a new design variable in steel material selection. By controlling density the engineering properties of steel components may be altered significantly: improvement in the weight-to-stiffness ratio is particularly pronounced, as is the available energy dissipation and thermal resistivity. Full-scale applications of steel foams in civil structures have not yet been demonstrated. Therefore, existing applications demonstrating either proof-of-concept for steel foam, or full-scale use of aluminum foams in situations with clear civil/structural analogs are highlighted. Adoption of steel foam relies on the manufacturing method, particularly its cost, and the resulting properties of the steel foam. Therefore, published methods for producing steel foam are summarized, along with measurements of steel foam structural (modulus, yield stress, etc.) and non-structural (thermal conductivity, acoustic absorption, etc.) properties. Finally, existing models for predicting foamed steel material properties are summarized to highlight the central role of material density. Taken in total the existing research demonstrates the viability of steel foams for use in civil/structural applications, while also pointing to areas where further research work is required.