The impact of voluntary environmental protection instruments on company environmental performance

In the last decade there has been increasing emphasis on the use of voluntary environmental protection tools such as corporate environmental reporting (CER) and environmental management systems (EMSs). There has been relatively little research, however, on the impact of these tools on the actual environmental performance of companies. This paper presents the findings of a survey of 40 companies operating in Western Australia to determine the extent to which the implementation of two voluntary instruments has influenced company environmental performance. The research considered four questions: To what extent have CER and EMSs influenced the environmental performance of companies operating in Western Australia? What are the characteristics of these influences? How does the influence of EMSs on environmental performance compare to that of CER? Have other external factors concurrently influenced environmental performance? In general, most respondents indicated that EMSs had influenced environmental management practices to some extent. On the other hand, CER was seen more as a public relations exercise and had less impact on company practices compared with EMSs. Other factors that influenced environmental performance included pressure from clients, senior management, the public and regulators; corporate culture; and cost savings

Linguistic Reflection in Java

Reflective systems allow their own structures to be altered from within. Here we are concerned with a style of reflection, called linguistic reflection, which is the ability of a running program to generate new program fragments and to integrate these into its own execution. In particular we describe how this kind of reflection may be provided in the compiler-based, strongly typed object-oriented programming language Java. The advantages of the programming technique include attaining high levels of genericity and accommodating system evolution. These advantages are illustrated by an example taken from persistent programming which shows how linguistic reflection allows functionality (program code) to be generated on demand (Just-In-Time) from a generic specification and integrated into the evolving running program. The technique is evaluated against alternative implementation approaches with respect to efficiency, safety and ease of use.Comment: 25 pages. Source code for examples at http://www-ppg.dcs.st-and.ac.uk/Java/ReflectionExample/ Dynamic compilation package at http://www-ppg.dcs.st-and.ac.uk/Java/DynamicCompilation

Sideslip estimation for articulated heavy vehicles at the limits of adhesion

Various active safety systems proposed for articulated heavy goods vehicles (HGVs) require an accurate estimate of vehicle sideslip angle. However in contrast to passenger cars, there has been minimal published research on sideslip estimation for articulated HGVs. State-of-the-art observers, which rely on linear vehicle models, perform poorly when manoeuvring near the limits of tyre adhesion. This paper investigates three nonlinear Kalman filters (KFs) for estimating the tractor sideslip angle of a tractor–semitrailer. These are compared to the current state-of-the-art, through computer simulations and vehicle test data. An unscented KF using a 5 degrees-of-freedom single-track vehicle model with linear adaptive tyres is found to substantially outperform the state-of-the-art linear KF across a range of test manoeuvres on different surfaces, both at constant speed and during emergency braking. Robustness of the observer to parameter uncertainty is also demonstrated.Engineering and Physical Sciences Research Council, Cambridge Vehicle Dynamics Consortiu

Compaction and tensile forces determine the accuracy of folding landscape parameters from single molecule pulling experiments

We establish a framework for assessing whether the transition state location of a biopolymer, which can be inferred from single molecule pulling experiments, corresponds to the ensemble of structures that have equal probability of reaching either the folded or unfolded states (Pfold = 0.5). Using results for the forced-unfolding of a RNA hairpin, an exactly soluble model and an analytic theory, we show that Pfold is solely determined by s, an experimentally measurable molecular tensegrity parameter, which is a ratio of the tensile force and a compaction force that stabilizes the folded state. Applications to folding landscapes of DNA hairpins and leucine zipper with two barriers provide a structural interpretation of single molecule experimental data. Our theory can be used to assess whether molecular extension is a good reaction coordinate using measured free energy profiles.Comment: 6 pages, 4 figures, Phys. Rev. Lett. (in press

Negative-energy perturbations in cylindrical equilibria with a radial electric field

The impact of an equilibrium radial electric field $E$ on negative-energy perturbations (NEPs) (which are potentially dangerous because they can lead to either linear or nonlinear explosive instabilities) in cylindrical equilibria of magnetically confined plasmas is investigated within the framework of Maxwell-drift kinetic theory. It turns out that for wave vectors with a non-vanishing component parallel to the magnetic field the conditions for the existence of NEPs in equilibria with E=0 [G. N. Throumoulopoulos and D. Pfirsch, Phys. Rev. E 53, 2767 (1996)] remain valid, while the condition for the existence of perpendicular NEPs, which are found to be the most important perturbations, is modified. For $|e_i\phi|\approx T_i$ ($\phi$ is the electrostatic potential) and $T_i/T_e > \beta_c\approx P/(B^2/8\pi)$ ($P$ is the total plasma pressure), a case which is of operational interest in magnetic confinement systems, the existence of perpendicular NEPs depends on $e_\nu E$, where $e_\nu$ is the charge of the particle species $\nu$. In this case the electric field can reduce the NEPs activity in the edge region of tokamaklike and stellaratorlike equilibria with identical parabolic pressure profiles, the reduction of electron NEPs being more pronounced than that of ion NEPs.Comment: 30 pages, late

Super-alfvenic propagation of cosmic rays: The role of streaming modes

Numerous cosmic ray propagation and acceleration problems require knowledge of the propagation speed of relativistic particles through an ambient plasma. Previous calculations indicated that self-generated turbulence scatters relativistic particles and reduces their bulk streaming velocity to the Alfven speed. This result was incorporated into all currently prominent theories of cosmic ray acceleration and propagation. It is demonstrated that super-Alfvenic propagation is indeed possible for a wide range of physical parameters. This fact dramatically affects the predictions of these models

Relationship between heavy vehicle speed limit and fleet fuel consumption on minor roads

This paper investigates the traffic-related effects of a proposal to increase the speed limit from 40 mile/h to 50 mile/h, for heavy goods vehicles greater than 7.5 tonnes, on single carriageway roads. A ‘microscopic’ single carriageway traffic simulation is developed by combining the ‘enhanced intelligent driver model’ with a single carriageway gap-acceptance passing model. Fuel consumption estimates are made using engine characteristic maps and a ‘fuel optimal’ gear selection scheme, where vehicle trajectories from the traffic simulations are taken as input drive-cycles. Traffic congestion and fleet fuel consumption are specifically addressed, though implications regarding passing behaviour and traffic safety are also noted. Results indicate that the proposed 50 mile/h heavy goods vehicles speed limit would reduce traffic congestion by over 37% and increase fleet fuel consumption by approximately 0.5 L/100 km. The authors would like to thank Justin Bishop and Niall Martin of Cambridge University Engineering Department for providing valuable data. The authors would also like to thank Rachael Dillon of Freight Transport Association for suggesting the project. This work was supported in part by the Centre for Sustainable Road Freight (SRF) and the Engineering and Physical Sciences Research Council (EPSRC) through Grant Ref EP/K00915X/1. At the time of writing, the members of the SRF were: Coca-Cola Enterprises, Denby Transport, DHL, Freight Transport Association, Haldex Brake Products, Goodyear Tires, John Lewis/Waitrose, Laing O’Rourke, Optrak, SDC Trailers, Tesco, Volvo Trucks, Warburtons, Wincanton.This is the accepted manuscript for a paper published in the Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, DOI: 10.1177/0954406215573038

Expanded Very Large Arrays Observations of a Proto-Cluster of Molecular Gas-Rich Galaxies at z = 4.05

We present observations of the molecular gas in the GN20 proto-cluster of galaxies at z = 4.05 using the Expanded Very Large Array (EVLA). This group of galaxies is the ideal laboratory for studying the formation of massive galaxies via luminous, gas-rich starbursts within 1.6 Gyr of the big bang. We detect three galaxies in the proto-cluster in CO 2-1 emission, with gas masses (H_2) between 10^(10) and 10^(11) × (α/0.8) M_⊙. The emission from the brightest source, GN20, is resolved with a size ~2'' and has a clear north-south velocity gradient, possibly indicating ordered rotation. The gas mass in GN20 is comparable to the stellar mass (1.3 × 10^(11) × (α/0.8) M_⊙ and 2.3 × 10^(11) M_⊙, respectively), and the sum of gas plus stellar mass is comparable to the dynamical mass of the system (~3.4 × 10^(11)[sin (i)/sin (45°)]^(–2) M_⊙), within a 5 kpc radius. There is also evidence for a tidal tail extending another 2'' north of the galaxy with a narrow velocity dispersion. GN20 may be a massive, gas-rich disk that is gravitationally disturbed, but not completely disrupted. There is one Lyman-break galaxy (BD29079) in the GN20 proto-cluster with an optical spectroscopic redshift within our search volume, and we set a 3σ limit to the molecular gas mass of this galaxy of 1.1 × 10^(10) × (α/0.8) M_⊙