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Article
Publication date: 1 October 2002

R.V. Balendran, T.M. Rana, T. Maqsood and W.C. Tang

The inclusion of pozzolans like pulverised fuel ash (PFA), silica fume (SF) and metakaolin (MK) enhances the properties of concrete both in fresh and hardened states. In the case…

805

Abstract

The inclusion of pozzolans like pulverised fuel ash (PFA), silica fume (SF) and metakaolin (MK) enhances the properties of concrete both in fresh and hardened states. In the case of high performance concrete (HPC), their role in enhancing the workability, strength and durability is extremely significant. However HPC has been observed to be more vulnerable than normal strength concrete when exposed to elevated temperatures. This paper presents an overview and discusses the strength and durability performance of high‐performance pozzolanic concretes incorporating PFA, SF, and MK subjected to elevated temperatures. Various researchers have demonstrated that addition of silica fume causes HPC to perform poorly when subjected to elevated temperatures. Higher loss of strength and spalling risks are also associated with it. Addition of PFA and MK has been found to improve the fire performance of HPC both in terms of residual strength and durability.

Details

Structural Survey, vol. 20 no. 4
Type: Research Article
ISSN: 0263-080X

Keywords

Article
Publication date: 1 June 2005

Steen Koekebakker and Fridthjof Ollmar

The forward curve dynamics in the Nordic electricity market is examined. Six years of price data on futures and forward contracts traded in the Nordic electricity market are…

1349

Abstract

The forward curve dynamics in the Nordic electricity market is examined. Six years of price data on futures and forward contracts traded in the Nordic electricity market are analysed. For the forward price function of electricity, we specify a multi‐factor term structure models in a Heath‐Jarrow‐Morton framework. Principal component analysis is used to reveal the volatility structure in the market. A two‐factor model explains 75 per cent of the price variation in our data, compared to approximately 95 per cent in most other markets. Further investigations show that correlation between short‐ and long‐term forward prices is lower than in other markets. We briefly discuss possible reasons why these special properties occur, and some consequences for hedging exposures in this market.

Details

Managerial Finance, vol. 31 no. 6
Type: Research Article
ISSN: 0307-4358

Keywords

Article
Publication date: 1 December 2020

Rui Lin, Haibo Huang and Maohai Li

This study aims to present an automated guided logistics robot mainly designed for pallet transportation. Logistics robot is compactly designed. It could pick up the pallet…

Abstract

Purpose

This study aims to present an automated guided logistics robot mainly designed for pallet transportation. Logistics robot is compactly designed. It could pick up the pallet precisely and transport the pallet up to 1,000 kg automatically in the warehouse. It could move freely in all directions without turning the chassis. It could work without any additional infrastructure based on laser navigation system proposed in this work.

Design/methodology/approach

Logistics robot should be able to move underneath and lift up the pallet accurately. Logistics robot mainly consists of two sub-robots, like two forks of the forklift. Each sub-robot has front and rear driving units. A new compact driving unit is compactly designed as a key component to ensure access to the narrow free entry of the pallet. Besides synchronous motions in all directions, the two sub-robots should also perform synchronous lifting up and laying down the pallet. Logistics robot uses a front laser to detect obstacles and locate itself using on-board navigation system. A rear laser is used to recognize and guide the sub-robots to pick up the pallet precisely within ± 5mm/1o in x-/yaw direction. Path planning algorithm under different constraints is proposed for logistics robot to obey the traffic rules of pallet logistics.

Findings

Compared with the traditional forklift vehicles, logistics robot has the advantages of more compact structure and higher expandability. It can realize the omnidirectional movement flexibly without turning the chassis and take zero-radius turn by controlling compact driving units synchronously. Logistics robot can move collision-free into any pallet that has not been precisely placed. It can plan the paths for returning to charge station and charge automatically. So it can work uninterruptedly for 7 × 24 h. Path planning algorithm proposed can avoid traffic congestion and improve the passability of the narrow roads to improve logistics efficiencies. Logistics robot is quite suitable for the standardized logistics factory with small working space.

Originality/value

This is a new innovation for pallet transportation vehicle to improve logistics automation.

Details

Assembly Automation, vol. 41 no. 1
Type: Research Article
ISSN: 0144-5154

Keywords

Article
Publication date: 9 November 2015

Martina Mysíková

The purpose of this paper is to focus on earnings inequality within dual-earner couples in four Central-East European (CEE) countries: the Czech Republic, Hungary, Poland, and…

Abstract

Purpose

The purpose of this paper is to focus on earnings inequality within dual-earner couples in four Central-East European (CEE) countries: the Czech Republic, Hungary, Poland, and Slovakia. It aims to analyse the factors that influence earnings distribution within couples.

Design/methodology/approach

The analysis uses OLS regression applied on the Statistics on Income and Living Conditions 2011 survey to reveal the various influence of relevant factors, especially relative education and the presence of children, on relative earnings.

Findings

Women, on average, contribute less to a couple’s income than men. While considerably higher in the Czech Republic and Slovakia, such disparity is relatively low in Hungary and Poland. These countries have the highest share of dual-earner couples where the woman outearns her partner. The factor that substantially reduces the within-couple earnings inequality in all the analysed countries is a higher relative education of women. On the contrary, the presence of children, especially those of younger age, increases this disparity in the Czech Republic and Slovakia.

Originality/value

The research on within-couple earning inequality in CEE countries lags behind the relatively rich evidence from western Europe. This is the first study which systematically describes the situation in CEE countries from a comparative perspective.

Details

Journal of Economic Studies, vol. 42 no. 6
Type: Research Article
ISSN: 0144-3585

Keywords

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