Study of the digestion process at a full-scale solid-state biogas plant by using ORWARE: Model modification and implementation.

The configuration of the reactor influences the digestion process and thus the product yields; other factors such as the rate of biogas production or biogas loss also affect the process specifically with high solid configuration. With these in mind, the ORganic WAste REsearch (ORWARE) anaerobic digestion sub-model was modified to be able to study solid-state anaerobic digestion (SS-AD) (using plug-flow reactor). The simulation results from the updated model agreed with the operational data with respect to methane yield, digestate yield and energy turnover.

Life cycle assessment of upgrading options of a preliminary wastewater treatment plant including food waste addition.

Life cycle assessment (LCA) is a beneficial tool to evaluate the performance of wastewater treatment plants (WWTPs) and to compare different upgrading options. The main objective of this study is to investigate the environmental impact of upgrading options of a preliminary WWTP in Istanbul, Turkey. The preliminary plant currently consists of mechanical treatment units and various upgrading options including primary treatment and high-rate activated sludge system (HRAS) process as well as the addition of food waste to wastewater were compared.

Horse manure as feedstock for anaerobic digestion.

Horse keeping is of great economic, social and environmental benefit for society, but causes environmental impacts throughout the whole chain from feed production to manure treatment. According to national statistics, the number of horses in Sweden is continually increasing and is currently approximately 360,000. This in turn leads to increasing amounts of horse manure that have to be managed and treated.

Enhancement of biogas production from food waste and sewage sludge - Environmental and economic life cycle performance.

Management of municipal solid waste is an efficient method to increase resource efficiency, as well as to replace fossil fuels with renewable energy sources due to that (1) waste to a large extent is renewable as it consists of food waste, paper, wood etc. and (2) when energy and materials are recovered from waste treatment, fossil fuels can be substituted. In this paper results from a comprehensive system study of future biological treatment of readily degradable waste in two Swedish regions are presented.

Multiple system modelling of waste management.

Due to increased environmental awareness, planning and performance of waste management has become more and more complex. Therefore waste management has early been subject to different types of modelling. Another field with long experience of modelling and systems perspective is energy systems.

Models for waste life cycle assessment: review of technical assumptions.

A number of waste life cycle assessment (LCA) models have been gradually developed since the early 1990 s, in a number of countries, usually independently from each other. Large discrepancies in results have been observed among different waste LCA models, although it has also been shown that results from different LCA studies can be consistent. This paper is an attempt to identify, review and analyse methodologies and technical assumptions used in various parts of selected waste LCA models.

Simulation of reflected light intensity changes during navigation and radio-frequency lesioning in the brain.

An electrode with adjacent optical fibers for measurements during navigation and radio frequency lesioning in the brain is modeled for Monte Carlo simulations of light transport in brain tissue. Relative reflected light intensity at 780 nm, I780, from this electrode and probes with identical fiber configuration are simulated using the intensity from native white matter as reference. Models are made of homogeneous native and coagulated gray, thalamus, and white matter as well as blood.

Combined diffuse light reflectance and electrical impedance measurements as a navigation aid in deep brain surgery.

Aim: The aim of this study is to assess reflected light intensity combined with impedance as a navigation aid during stereotactic neurosurgery.

Methods: During creation of 21 trajectories for stereotactic implantation of deep brain stimulation electrodes in the globus pallidus internus or subthalamus (zona incerta or subthalamic nucleus), impedance at 512 kHz and reflected light intensity at 780 nm were measured continuously and simultaneously with a radio frequency electrode containing optical fibres. The signals were compared with the anatomy, determined from pre- and post-operative MRI and CT.

Diffuse reflectance spectroscopy measurements for tissue-type discrimination during deep brain stimulation.

Diffuse reflectance spectroscopy as a method for improving intracerebral guidance during functional neurosurgery has been investigated. An optical probe was developed for measurements during stereotactic and functional neurosurgery in man. The aim of the study was to investigate the spectral differences between white and grey matter and between white matter and functional targets.

A laser Doppler system for intracerebral measurements during stereotactic neurosurgery.

A laser Doppler system for intracerebral measurements during stereotactic and functional neurosurgery is presented. The system comprises a laser Doppler perfusion monitor, an optical probe adapted for the Leksell Stereotactic System and a personal computer with software for acquisition, data analysis and presentation. The software makes it possible to present both the perfusion and the total backscattered light intensity (TLI) in real-time.

Intracerebral microvascular measurements during deep brain stimulation implantation using laser Doppler perfusion monitoring.

The aim of the study was to investigate if laser Doppler perfusion monitoring (LDPM) can be used in order to differentiate between gray and white matter and to what extent microvascular perfusion can be recorded in the deep brain structures during stereotactic neurosurgery. An optical probe constructed to fit in the Leksell Stereotactic System was used for measurements along the trajectory and in the targets (globus pallidus internus, subthalamic nucleus, zona incerta, thalamus) during the implantation of deep brain stimulation leads (n = 22). The total backscattered light intensity (TLI) reflecting the grayness of the tissue, and the microvascular perfusion were captured at 128 sites.

What life-cycle assessment does and does not do in assessments of waste management.

In assessments of the environmental impacts of waste management, life-cycle assessment (LCA) helps expanding the perspective beyond the waste management system. This is important, since the indirect environmental impacts caused by surrounding systems, such as energy and material production, often override the direct impacts of the waste management system itself. However, the applicability of LCA for waste management planning and policy-making is restricted by certain limitations, some of which are characteristics inherent to LCA methodology as such, and some of which are relevant specifically in the context of waste management.

Flexible and robust strategies for waste management in Sweden.

Treatment of solid waste continues to be on the political agenda. Waste disposal issues are often viewed from an environmental perspective, but economic and social aspects also need to be considered when deciding on waste strategies and policy instruments. The aim of this paper is to suggest flexible and robust strategies for waste management in Sweden, and to discuss different policy instruments.

Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling, simulation and analysis of parameter influence and interaction.

Radio-frequency brain lesioning is a method for reducing e.g. symptoms of movement disorders.

Optical measurements during experimental stereotactic radiofrequency lesioning.

The aim of this study was to evaluate in vivo a laser Doppler measurement system in porcine brain tissue during thermal lesioning. A 2-mm monopolar radiofrequency lesioning electrode was equipped with optical fibers in order to monitor the lesioning procedure. Laser Doppler and backscattered light intensity signals were measured along the electrode trajectory and during bilateral lesioning in the central gray (70, 80 and 90 degrees C, n = 14).

The effect of cystic cavities on deep brain stimulation in the basal ganglia: a simulation-based study.

Although the therapeutic effect of deep brain stimulation (DBS) is well recognized, a fundamental understanding of the mechanisms responsible is still not known. In this study finite element method (FEM) modelling and simulation was used in order to study relative changes of the electrical field extension surrounding a monopolar DBS electrode positioned in grey matter. Due to the frequently appearing cystic cavities in the DBS-target globus pallidus internus, a nucleus of grey matter with and without a cerebrospinal fluid filled cystic cavity was modelled.

Radio frequency electrode system for optical lesion size estimation in functional neurosurgery.

Radiofrequency (RF) lesioning in the human brain is one possible surgical therapy for severe pain as well as movement disorders. One obstacle for a safer lesioning procedure is the lack of size monitoring. The aim of this study was to investigate if changes in laser Doppler or intensity signals could be used as markers for size estimation during experimental RF lesioning.

How model-based systems analysis can be improved for waste management planning.

Waste management models have been developed worldwide since the late 1960s. The overall aim of the models is to assist decision makers who are facing a complex task in order to handle waste in a cost-efficient and environmentally sound way. International research publications regarding waste management models point out the major benefits to be their capacity to deal with complexity and uncertainty and of finding benefits of co-operation and handling different goals.

Experimental radiofrequency brain lesions: a volumetric study.

Objective: This study describes the production, under strictly standardized and controlled conditions, of radiofrequency lesions with identical neurogenerator settings: in vitro in two different albumin solutions (nongelatinous and gelatinous) and in vivo in the thalamus of the pig.

Methods: The radiofrequency lesions were investigated in vitro by the use of a specially designed video system and in vivo by magnetic resonance imaging. Moreover, the size of the in vivo lesions was estimated with the use of histological sectioning.