An analysis of construction productivity in Malaysia

The construction industry is an industry of major strategic importance. Its level of productivity has a significant effect on national economic growth. Productivity indicators are examined. The indicators consist of labour productivity, capital productivity, labour competitiveness, capital intensity and added value content of data, which are obtained from the published census/biannual surveys of the construction industry between the years 1999 and 2011 from the Department of Statistics of Malaysia. The results indicated that there is an improvement in the labour productivity, but the value-added content is declining. The civil engineering and special trades subsectors are more productive than the residential and non-residential subsectors in terms of labour productivity because machine-for-labour substitution is a more important process in those subsectors. The capital-intensive characteristics of civil engineering and special trade works enable these subsectors to achieve higher added value per labour cost but not the capital productivity. The added value per labour cost is lower in larger organizations despite higher capital productivity. However, the capital intensity is lower and unit labour cost is higher in the larger organizations.     

Economic development and construction productivity in Malaysia

The productivity of the construction industry has a significant effect on national economic growth. Gains from higher construction productivity flow through the economy, as all industries rely on construction to some extent as part of their business investment. Contractions and expansions of economic activity are common phenomena in an economy. Three construction cycles occurred between the years 1970 and 2011 in Malaysia. The relationships between construction productivity and economic development are examined by the partial correlation method to establish the underlying factors driving the change in construction productivity. Construction productivity is statistically significantly correlated with gross domestic product (GDP) per capita in a positive direction for the 1985–98 and 1998–2009 cycles, but not the 1970–85 cycle. Fluctuations in construction activities and the influx of foreign workers underlie the changes of construction productivity in the 1985–98 cycle. There was less fluctuation in construction activities in the 1998–2009 cycle, with changes being mainly due to the fiscal stimulation policies of the government in attempting to stabilize the economy. The intensive construction of mega-projects resulted in resource constraints and cost pressures during the 1980s and 1990s. A better management of the ‘boom-bust’ nature of the construction business cycle is required to maintain the capability and capacity of the industry.     

Architecture,the city and its scale: Oscar Niemeyer in Tripoli,Lebanon

Drawing on a theoretical concept of scalar individuation in which the genesis of scale is understood according to ontological, epistemic and discursive registers, this paper deploys the notion of scale as a problematic in order to open a new space for critical insight into a little-known project by Oscar Niemeyer, the Rachid Karame Fair and Exposition site in Tripoli, Lebanon. It argues against the idea of unity, in terms of authorship and reception, put forward by proponents and critics of modernism. It demonstrates the way different and often paradoxical forms of scalar rationality can co-exist within a single project. Moreover, the individuation of specific scalar problems within the project are located within an historical context that reveals the inherently contingent nature of architectural claims with respect to the political.     

Prediction of the crack condition of highway pavements using machine learning models

Departments of Transportation regularly evaluate the condition of pavements through visual inspections, nondestructive evaluations, image recognition models and learning algorithms. The above methodologies, though efficient, have drawn attention due to their subjective errors, uncertainties, noise effects and overfitting. To improve on the outcomes of the shallow learning models already used in pavement crack prediction, this paper reports on an investigation of the use of recursive partitioning and artificial neural networks (ANN; deep learning frameworks) in predicting the crack rating of pavements. Explanatory variables such as the average daily traffic and truck factor, roadway functional class, asphalt thickness, and pavement condition time series data are employed in the model formulation. Overall, it is observed that the recursive partitioning (regression tree – R² > 0.8 and classification tree – R² > 0.6) and ANN (continuous response – R² > 0.8 and categorical response – R² > 0.6) are compelling machine learning models for the prediction of the crack ratings based on their goodness-of-fit statistics, mean absolute deviation (MAD < 0.4) and the root mean square errors (RMSE between 0.30 and 0.65).     

The utility of energy storage to improve the economics of wind–diesel power plants in Canada

Wind energy systems have been considered for Canada's remote communities in order to reduce their costs and dependence on diesel fuel to generate electricity. Given the high capital costs, low-penetration wind–diesel systems have been typically found not to be economic. High-penetration wind–diesel systems have the benefit of increased economies of scale, and displacing significant amounts of diesel fuel, but have the disadvantage of not being able to capture all of the electricity that is generated when the wind turbines operate at rated capacity.Two representative models of typical remote Canadian communities were created using HOMER, an NREL micro-power simulator to model how a generic energy storage system could help improve the economics of a high-penetration wind–diesel system. Key variables that affect the optimum system are average annual wind speed, cost of diesel fuel, installed cost of storage and a storage systems overall efficiency. At an avoided cost of diesel fuel of 0.30 $Cdn/kWh and current installed costs, wind generators are suitable in remote Canadian communities only when an average annual wind speed of at least 6.0 m/s is present. Wind energy storage systems become viable to consider when average annual wind speeds approach 7.0 m/s, if the installed cost of the storage system is less than 1000 $Cdn/kW and it is capable of achieving at least a 75% overall energy conversion efficiency. In such cases, energy storage system can enable an additional 50% of electricity from wind turbines to be delivered.     

Illicit drug consumption estimations derived from wastewater analysis: A critical review

The consumption of illicit drugs causes indisputable societal and economic damage. Therefore it is necessary to know their usage levels and trends for undertaking targeted actions to reduce their use. Recently, a new approach (namely sewage epidemiology) was developed for the estimation of illicit drug use based on measurements of urinary excreted illicit drugs and their metabolites in untreated wastewater. This review aims at critically evaluating the published literature and identifying research gaps of sewage epidemiology. Firstly, the existing analytical procedures for the determination of the four most used classes of illicit drugs worldwide (cannabis, cocaine, opiates and amphetamine-like stimulants) and their metabolites in wastewater are summarized and discussed. The focus lies on the sample preparation and on the analysis with chromatographic techniques coupled to mass spectrometry. Secondly, back-calculations used to transform measured concentrations in wastewater (in ng/L) into an amount of used illicit drug (in g/day per 1000 inhabitants or doses/day per 1000 inhabitants) are discussed in detail for the four groups of illicit drugs. Sewage epidemiology data from Spain, Belgium, UK, Italy, Switzerland and USA are summarized and compared with data from international organisations, such as the European Monitoring Centre for Drug and Drug Addiction (EMCDDA) and the United Nations Office on Drugs and Crime (UNODC). The results derived from wastewater analysis show in general good agreement with existing prevalence data (percentage of a population that uses illicit drugs at a given time) and demonstrate the potential of sewage epidemiology. However, this review confirms that future work should focus on further optimisation and standardisation of various important parameters (e.g. sample collection and back-calculations). In the future, sewage epidemiology could be used in routine drug monitoring campaigns as a valuable tool in addition to the classical socio-epidemiological studies for the determination of local, national and international illicit drug use.     

中国城市无意识下形成的四种空间类型

一种城市主义的批判性实践不应执着于不相干的美学自主性,而应着眼于作为当代城市化主要征象的四种空间类型:位于城市与农村之间界定模糊区域的工厂区;纵横全国的基础设施管线和网络;新型文化聚落、邻里和建筑物;来自农村而在城市工作的新城市主体所形成的心理与社会网络。     

Properties of Light MMCs Modified with Cordierite Synthesized from Fly Ash

This paper presents novel opportunities for management of fly ash by synthesizing the material into cordierite ceramics and using it as a reinforcing phase for light metal alloys. Metal matrix composites (based on magnesium alloy and aluminum alloy) were produced by squeeze casting. The magnesium matrix composites with a suitably selected reinforcing phase content (2 wt.%) exhibited much better strength properties than the unmodified alloy (AM60). It was also demonstrated that the wettability (or the lack thereof) in the metal-ceramic system is critical to successful production of the composites based on the AK7 alloy with cordierite. Light alloy matrix composites reinforced with cordierite ceramics particles are innovative materials that combine high strength with low weight, which may be a key factor of merit for numerous applications of the composite in various branches of industries.     

Estimation of heat transfer coefficient of forced-air cooling and its experimental validation in controlled processing of forgings

Estimation of the cooling efficiency of an accelerated air for the needs of cooling of die forgings is presented. Temperature dependence of heat transfer coefficient (HTC) was calculated for different cooling conditions varied by airflow velocity, covering the range from 18 to 48?m/s. Time–temperature measurements performed on a full-scale semi-industrial cooling line provided similarity to conditions typical of industrial conveyor, which gives the results utilitarian significance in design of controlled processing (of steel forged products). Acquired HTC values, ranging from 164.7 to 298?W/m²?·?K, were validated in numerical simulation of cooling complex-shape forgings and subject to experimental verification, indicating perfect agreement with physical measurements.     

Analytic solution for planar indeterminate impact problems using an energy constraint

This work proposes an analytic method for resolving planar multi-point indeterminate impact problems for rigid-body systems. An event-based approach is used to detect impact events, and constraints consistent with the rigid-body assumption are used to resolve the indeterminacy associated with multi-point impact analysis. The work-energy relation is utilized to determine post-impact velocities based on an energetic coefficient of restitution to model energy dissipation, thereby yielding an energetically consistent set of post-impact velocities based on Stronge’s energetic coefficient of restitution for the treatment of rigid impacts. The effect of stick–slip transition is analyzed based on Coulomb friction. This paper also discusses the transition from impact to contact. This analysis is essential for considering the rocking block problem that is used as an example herein. The predictions of the model for the rocking block problem are compared to experimental results published in the literature. An example of a planar ball undergoing two-point impact is also presented.