In-Situ Sizing of Powders and Crystals using Phase Doppler Technique

ABSTRACT

ABSTRACT Phase Doppler technique measures the velocity of single particles based on the frequency of oscillations in the light scattered by the particles. The phase shift between two oscillatory signals, collected by two spatially separated detectors, is used as a statistical measure of panicle size. It is shown experimentally that the second and fourth moments of phase shift distribution increase linearly with the second and fourth power of aerodynamic size D of irregular particles, provided that the aspect ratio is small. This allows one to determine the mean and standard deviation of D² in real time without taking a sample. The above result is based on combined measurements using the phase Doppler technique and the aerodynamic particle sizer, and has been consistent for a variety of particles, including alumina, com starch, quartz, and dust. Measurements were also taken to examine the growth and dynamics of crystals, while cooling down a solution of lysine monohydrochloride in a mixture of methanol and water. These data will also be presented and discussed.     

MODELING AND OPTIMIZATION OF SINGLE-ELEMENT BULK SiGe THIN-FILM COOLERS

Abstract

Modeling and optimization of bulk SiGe thin-film coolers are described. Thin-film coolers can provide large cooling power densities compared to commercial thermoelectrics. Thin-film SiGe coolers have been demonstrated with maximum cooling of 4°C at room temperature and with cooling power density exceeding 500 W/cm². Important parameters in the design of such coolers are investigated theoretically and are compared with experimental data. Thermoelectric cooling, joule heating, and heat conduction are included in the model as well as non-ideal effects such as contact resistance, geometrical effects, and three-dimensional thermal and electrical spreading resistance of the substrate. Simulations exhibit good agreement with experimental results for bulk Si and SiGe thin-film coolers. It turned out that in many spot cooling applications using two n- and p-elements electrically in series and thermally in parallel does not give significant improvement over single leg elements. This is in contrast to conventional thermoelectric modules and is due to the aspect ratio and special geometry of thin film coolers. With optimization of SiGe thin-film cooler, simulations predict it can provide over 16°C with cooling power density of over 2000 W/cm².     

Housing Vacancy and the Shrinking City: Trends and Policies in the UK and the City of Liverpool

In the context of the discourse around shrinking cities, the aim of the paper was to try and better understand and differentiate the various types and causes of urban housing vacancy and to ask whether policy responses including planning policies appropriately reflect this variety. The paper briefly discusses the issue of shrinking cities, before considering theoretical explanations for housing vacancy and examining the relationships between population change, housing vacancy and policy responses in the Liverpool conurbation. Conclusions are then drawn about the nature of housing vacancy and the effectiveness of policy responses.     

Segmenting sensor data for activity monitoring in smart environments

Within a smart environment, sensors have the ability to perceive changes of the environment itself and can therefore be used to infer high-level information such as activity behaviours. Sensor events collected over a period of time may contain several activities. The fundamental process of any automatic activity monitoring system is therefore to process streams of sensor events and detect occurrences of activities. In this study, we propose three segmentation algorithms to separate time series sensor data into segments to be further processed by an activity recognition algorithm. A preliminary evaluation of the approaches developed has been conducted on a data set collected from a single person living in an apartment over a period of 28 days. The results show that the proposed approaches can segment sensor data to detect activities and infer sensor segments to recognise activities with accuracies of 81.6, 81.6 and 82.9%, respectively.     

Re-engineering the construction process in the speculative house-building sector

The UK house-building industry has often been criticized for failing to meet the housing needs of the country. The traditional craft-based build process is labour intensive with a long lead-time and is difficult to control for product quality. It is also not suitable for configurable designs that would help to customize the home, and the industry has been criticized for excessive standardization of its products. Attempts at industrialization, usually employing frame or panel-based build methods seen in many countries, have failed due mainly to lack of clear objectives. A change in build technology is also only one step in addressing the concerns of poor quality and lack of product variety. The paper presents a programme of work that is being carried out with a major house builder towards re-engineering of the build process through a combination of new technology, product engineering and changes in working practices.     

Mind the gap: implications of overseas investment for regional house price divergence in Britain

The UK has had a long-standing regional house price gap with prices in London much higher than the rest of the UK. Using price data from 1969 to 2016 we track price differentials through several cycles of boom and bust, and note the growing divergence of London, particularly central London, from the rest of Britain. In explaining this divergence, we highlight the growing importance of international investment since the global financial crisis. We conclude that, although ‘Brexit’ may have brought the latest long London boom to a close, there is nothing to suggest that the regional house price gap will close. Given the ongoing importance of global financial inflows to major world cities, this has significant implications for how governments approach affordability and housing policy.     

Synthesis of a Bioreversibly Masked Lipophilic Adenosine Diphosphate Ribose Derivative

The design of a bioreversibly protected lipophilic sugar nucleotide as a potential membrane‐permeable precursor of adenosine diphosphate ribose (ADPR) is described. ADPR is the most potent activator of the transient receptor potential melastatin 2 (TRPM2) ion channel. Membrane‐permeable, lipophilic derivatives of ADPR are of great interest as tools for study of the mechanism of TRPM2. The approach described here was based on our recently disclosed “DiPPro” and “TriPPPro” prodrug approaches developed for the intracellular delivery of nucleotides. A lipophilic, bioreversibly masked ADPR analogue containing an enzymatically cleavable 4‐pentanoyloxybenzyl (PB) mask at the phosphate moiety next to the 5′‐position of adenosine, together with O‐acetyl groups, was prepared in high yields. Chemical and enzymatic hydrolysis studies in phosphate buffer (pH 7.3) were performed to assess chemical stability and possible (selective) enzymatic demasking of the ADPR analogue. HPLC‐MS revealed that the PB group was readily cleaved enzymatically. In addition, the formation of partially deacetylated ADPR compounds and also of fully unprotected ADPR was observed.     

Impacts of energy-efficiency investments on internal conditions in low-income households

Living in cold conditions poses a risk to health, in particular to low-income, fuel-poor households. Improving the energy efficiency of the housing stock may bring multiple positive health gains through improved indoor temperatures and reduced fuel consumption. This study used a multilevel interrupted time-series approach to evaluate a policy-led energy-performance investment programme. Long-term monitoring data were collected for intervention and control households at baseline (n?=?99) and follow-up (n?=?88), creating a dataset with 15,771 data points for a series of daily-averaged hydrothermal outcome variables. The study found that the intervention raised indoor air temperature by on average 0.84?K as compared with control households, thereby bringing the majority of indoor temperature measurements within the ‘healthy’ comfort zone of 18–24°C, while average daily gas usage dropped by 37%. External wall insulation was the most effective measure to increase indoor air temperature. The greatest increases were found in the evening and at night, in the bedroom, and in British steel-framed buildings. No evidence was found that the intervention substantially increased indoor relative humidity levels when accompanied by mechanical ventilation. The study concludes that the multilevel interrupted time-series approach offers a useful model for evaluating housing improvement programmes.