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This paper aims to compare and review alternative ways to adjust public ground leases.
Abstract
Purpose
This paper aims to compare and review alternative ways to adjust public ground leases.
Design/methodology/approach
Based on principles derived from a review of scientific literature, alternatives for the extension of leases are discussed based on the case of Amsterdam.
Findings
Many alternatives lead public ground-lease systems to produce results that are the opposite of what they are intended to be (as inspired by Henry George): new improvements result in higher rent, but additional location values do not result in higher rent. One exception is the lease-adjustment-at-property-transaction alternative, which may nevertheless result in fewer transactions.
Social implications
Public leasehold systems are highly contested with regard to the extension of leases. Such systems are often aimed at capturing land-value gains. In practice, however, this tends to be more difficult than expected. Value capture by authorities, as intended by the system, results in counter-movements of lessees, who often gain public support to set lower leases. These political processes may even result in the termination of such public ground-lease systems. This paper reports on a search for possible solutions.
Originality/value
The comparison of various alternatives to ground-lease extension based on principles derived from literature is new, and it contributes insight into public ground-lease systems.
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Kankan Ji, Xingquan Zhang, Shubao Yang, Liping Shi, Shiyi Wang and Yuguo Wu
The purpose of this paper is to evaluate surface integrity of quenched steel 1045 ground drily by the brazed cubic boron nitride (CBN) grinding wheel and the black SiC wheel…
Abstract
Purpose
The purpose of this paper is to evaluate surface integrity of quenched steel 1045 ground drily by the brazed cubic boron nitride (CBN) grinding wheel and the black SiC wheel, respectively. Surface integrity, including surface roughness, sub-surface hardness, residual stresses and surface morphology, was investigated in detail, and the surface quality of samples ground by two grinding wheels was compared.
Design/methodology/approach
In the present work, surface integrity of quenched steel 1045 machined by the CBN grinding wheel and the SiC wheel was investigated systematically. All the specimens were machined with a single pass in the down-cutting mode of dry condition. Surface morphology of the ground specimen was observed by using OLYMPUS BX51M optical microscopy. Surface roughness of seven points was measured by using a surface roughness tester at a cut-off length of 1.8 mm and the measurement traces were perpendicular to the grinding direction. Sub-surface micro-hardness was measured by using HVS-1000 digital micro-hardness tester after the cross-section surface was polished. The residual stress was tested by using X-350A X-ray stress analyzer.
Findings
When the cut depth is increased from 0.01 to 0.07 mm, the steel surface machined by the CBN wheel remains clear grinding mark, lower roughness, higher micro-hardness and higher magnitude of compressive stress and fine microstructure, while the surface machined by the SiC grinding wheel becomes worse with increasing of cut depth. The value of micro-hardness decreases, and the surface roughness increases, and the surface compressive stress turns into tensile stress. Some micro-cracks and voids occur when the sample is processed by the SiC grinding wheel with cut depth 0.07 mm.
Originality/value
In this paper, the specimens of quenched steel 1045 were machined by the CBN grinding wheel and the SiC wheel with various cutting depths. The processing quality resulted from the CBN grinding wheel is better than that resulted from the SiC grinding wheel.
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Julian King, Johnny Dow and Brendan Stevenson
The purpose of this paper is to analyse the clinical outcome data collected as part of an 18-week, abstinence-based residential therapeutic community (TC) programme, Higher Ground…
Abstract
Purpose
The purpose of this paper is to analyse the clinical outcome data collected as part of an 18-week, abstinence-based residential therapeutic community (TC) programme, Higher Ground Drug Rehabilitation Trust (Higher Ground) in New Zealand. Lessons and implications for routine collection of clinical outcome data are identified.
Design/methodology/approach
Higher Ground collects longitudinal data on all consenting clients using a battery of validated psychometric tools, with repeated measures at up to nine points in time from first presentation through to 12-month post-discharge follow up. Data analysis covered clients who entered Higher Ground between 1 July 2012 and 2 June 2015 (n=524).
Findings
Clients presented with histories of addiction which often had significant negative associations with their physical and psychological health, their relationships, work, accommodation and criminal behaviour. By the time they exited the programme, clinically and statistically significant improvements were seen across multiple indicators including: substance use and abstinence; symptoms of post-traumatic stress disorder, depression, anxiety and stress; and a range of social indicators.
Research limitations/implications
Attrition in follow-up research is a significant challenge, with people completing the TC programme being more likely to participate than those who do not. This limits generalizability in post-discharge data. There was no control group, making causal attribution a challenge. Identifying suitable benchmarks from the literature is challenging because of the variety of outcome measures and research methodologies used.
Practical implications
Tracking client outcomes longitudinally using psychometric tools is potentially valuable for TCs and their funding bodies, as it provides insights into patterns of client recovery that can inform ongoing service improvements and resource allocation decisions. However, significant challenges remain.
Originality/value
The study demonstrates the value, and practical challenges, of collecting high-quality outcome data in a TC setting.
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Ji Wang, Yuting Yan and Junming Li
Natural gas leak from underground pipelines could lead to serious damage and global warming, whose spreading in soil should be systematically investigated. This paper aims to…
Abstract
Purpose
Natural gas leak from underground pipelines could lead to serious damage and global warming, whose spreading in soil should be systematically investigated. This paper aims to propose a three-dimensional numerical model to analyze the methane–air transportation in soil. The results could help understand the diffusion process of natural gas in soil, which is essential for locating leak source and reducing damage after leak accident.
Design/methodology/approach
A numerical model using finite element method is proposed to simulate the methane spreading process in porous media after leaking from an underground pipe. Physical models, including fluids transportation in porous media, water evaporation and heat transfer, are taken into account. The numerical results are compared with experimental data to validate the reliability of the simulation model. The effects of methane leaking direction, non-uniform soil porosity, leaking pressure and convective mass transfer coefficient on ground surface are analyzed.
Findings
The methane mole fraction distribution in soil is significantly affected by the leaking direction. Horizontally and vertically non-uniform soil porosity has a stronger effect. Increasing leaking pressure causes increasing methane mole flux and flow rate on the ground surface.
Originality/value
Most existing gas diffusion models in porous media are for one- or two-dimensional simulation, which is not enough for predicting three-dimensional diffusion process after natural gas leak in soil. The heat transfer between gas and soil was also neglected by most researchers, which is very important for predicting the gas-spreading process affected by the soil moisture variation because of water evaporation. In this paper, a three-dimensional numerical model is proposed to further analyze the methane–air transportation in soil using finite element method, with the presence of water evaporation and heat transfer in soil.
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China is among one of the oldest civilizations in the world. The massive land mass of China also means that the Chinese people are subject to weather extremes as well as…
Abstract
China is among one of the oldest civilizations in the world. The massive land mass of China also means that the Chinese people are subject to weather extremes as well as topographical variety in a country which cuts across alpine heights, treacherous deserts, lush valleys, dusty plains and lengthy rivers. With these weather extremes as the backdrop, it is crucial for the Chinese people to develop appropriate environmental control techniques for their dwellings as well as to ensure the structural integrity of their buildings. This paper discusses the protection, heating, anti‐seismic and dampness techniques developed and implemented in ancient China. It also documents the measures taken by the ancient Chinese to ensure the structural integrity of their buildings. The examples highlighted in this paper suggest that the building science principles adopted in ancient China remain relevant in the construction industry today.
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IN its history, the aeroplane has rarely been considered prosaically as a transport vehicle, with the absolute acceptance of the implied requirements of public service, viz…
Abstract
IN its history, the aeroplane has rarely been considered prosaically as a transport vehicle, with the absolute acceptance of the implied requirements of public service, viz. safety, comfort, speed and punctuality.
Mingjing Jiang, Fang Liu, Huaning Wang and Xinxin Wang
The purpose of this paper is to present an investigation of the effect of different gravity conditions on the penetration mechanism using the two-dimensional Distinct Element…
Abstract
Purpose
The purpose of this paper is to present an investigation of the effect of different gravity conditions on the penetration mechanism using the two-dimensional Distinct Element Method (DEM), which ranges from high gravity used in centrifuge model tests to low gravity incurred by serial parabolic flight, with the aim of efficiently analyzing cone penetration tests on the lunar surface.
Design/methodology/approach
Seven penetration tests were numerically simulated on loose granular ground under different gravity conditions, i.e. one-sixth, one-half, one, five, ten, 15 and 20 terrestrial gravities. The effect of gravity on the mechanisms is examined with aspect to the tip resistance, deformation pattern, displacement paths, stress fields, stress paths, strain and rotation paths, and velocity fields during the penetration process.
Findings
First, under both low and high gravities, the penetration leads to high gradients of the value and direction of stresses in addition to high gradients in the velocity field near the penetrometer. In addition, the soil near the penetrometer undergoes large rotations of the principal stresses. Second, high gravity leads to a larger rotation of principal stresses and more downward particle motions than low gravity. Third, the tip resistance increases with penetration depth and gravity. Both the maximum (steady) normalized cone tip resistance and the maximum normalized mean (deviatoric) stress can be uniquely expressed by a linear equation in terms of the reciprocal of gravity.
Originality/value
This study investigates the effect of different gravity conditions on penetration mechanisms by using DEM.
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Richard P. Daisley and Boppana V. Chowdary
The purpose of this paper is to investigate the effects of liquid carbon dioxide (LCO2) on grinding of stainless steel.
Abstract
Purpose
The purpose of this paper is to investigate the effects of liquid carbon dioxide (LCO2) on grinding of stainless steel.
Design/methodology/approach
A factorial experimental approach was used to compare the LCO2's performance against grinding under dry air and emulsion coolants.
Findings
The experimental results have a great use to practitioners. It was found that under special conditions, LCO2 proves to be an alternative coolant for grinding of temperature sensitive materials. Furthermore, grinding under LCO2 conditions produced the lowest tangential force, while the normal forces were close to the values found under emulsion fluid environment. When compared to grinding under dry conditions, LCO2 coolant was successful in reducing the work piece temperatures. LCO2 and emulsion conditions inhibit work hardening by reducing material deformation at the grinding zone.
Originality/value
The paper shows that sub‐zero temperature coolants have the ability to bring about lower grinding temperatures than what is typically achieved under conventional fluids.
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EMO (the acronym for Exposition de la Machine Outil) is the biennial machine tool exhibition. It is held at the Hannover trade fair complex every fourth year. On alternate fourth…
Abstract
EMO (the acronym for Exposition de la Machine Outil) is the biennial machine tool exhibition. It is held at the Hannover trade fair complex every fourth year. On alternate fourth years the venue is either Paris or Milan.
JingHui Deng, Jinhe Chen and ZhengZhong Wang
The paper aims to establish a comprehensive optimization analysis model for a helicopter roll on the ground and take off based on optimal control method. The trajectory and…
Abstract
Purpose
The paper aims to establish a comprehensive optimization analysis model for a helicopter roll on the ground and take off based on optimal control method. The trajectory and control of the entire process are studied, and the key factors affecting the helicopter takeoff distance are analyzed.
Design/methodology/approach
First, based on the equivalent stiffness and damping, the landing gear model is established, and a six-degree-of-freedom helicopter model is formed. Then, the simulation of the roll-on takeoff is transformed into a nonlinear optimal control problem (NOCP). Meanwhile, a hybrid single-multiple shooting method-based transcription process is used for discretizing the problem, leading to a finite nonlinear programming model, which is solved by sequential quadratic programming. Finally, the process was calculated and compared with flight test data, which verified the feasibility of the NOCP. The influence of takeoff weight, takeoff power and liftoff airspeed on the takeoff distance of the helicopter was analyzed.
Findings
The results show that the takeoff weight can be increased by 17% under the maximum takeoff power, which is roll-on takeoff at an altitude of 0 m. When the helicopter takes off with the maximum weight at an altitude of 5000 m, the liftoff airspeed should be over 49.2 km/h.
Originality/value
The novelty of this paper lies in the comprehensive consideration of helicopter taxiing and taking-off phases, and the application of optimal control theory to establish a comprehensive analysis model, which can quickly analyze the maximum takeoff weight, takeoff distance, optimal liftoff speed and so on. Meanwhile, the method is verified based on the flight data.
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