High-speed optical modulator for application in instrumentation

The design and characterization of the first integrated optic modulator for a commercial instrument application are described. Alternative forms of modulation, including direct laser current modulation and optical heterodyne techniques, are reviewed for the application, which requires modulation to 20 GHz. The advantages of an integrated optic modulator fabricated using titanium in-diffused lithium niobate are discussed. Performance tradeoffs between x-cut and z-cut LiNbO₃ including bandwidth, modulation efficiency, bias point stability, and acoustic resonances are detailed. The x-cut device is found to give the best overall performance for this instrument application. Device reliability and testing, including temperature cycling, humidity, electrostatic discharge, mechanical shock, and vibration are described for complete packaged and pigtailed devices     

A 119 GHz planar Schottky diode mixer for a space application

A planar single-ended GaAs Schottky diode mixer has been designed, built, and tested at 119 GHz. The mixer front end includes also a waveguide filter for image rejection, and a temperature compensated ring filter. Measurements at room temperature showed a conversion loss of 7 dB and a noise temperature of 900 K (SSB). At 100 K the measured noise temperature of the mixer was 500 K (SSB).     

Thermally acceptable temperature drifts can reduce the energy consumption for cooling in office buildings

The energy consumption and cost in large office buildings can be reduced by allowing the indoor environment to deviate from the optimum comfort conditions to situations which are still acceptable by most occupants. One such strategy is to allow the indoor temperature to increase in the afternoon in summer. A computer program was developed to predict the thermal sensation and discomfort under transient conditions, and the detailed computer program BLAST was used to evaluate the indoor temperature, space cooling load, chilled water consumption and seasonal energy use. This paper presents a comparison performed for a reference office building in Montréal between a conventional design, with constant set-point temperature during the operating hours, and a new design, where the indoor temperature is allowed to increase after 3:00 p.m. The results show a reduction of seasonal consumption for chilled water between 34 and 40%, and a reduction of energy budget for HVAC systems of 11%.     

Effects of physical activity on the deposition of traffic-related particles into the human lungs in silico

Traffic-related particle emissions have been a great concern over a number of years due to their adverse health effects. In this research project, traffic-related particle deposition in the human lungs is studied using lung deposition estimates based on the ICRP 66 model. This study covers four human groups, i.e. adult males, adult females and two groups of children aged 5 and 10 years. The study examines particle deposition in the human lungs in relation to four different physical exercise levels, i.e. sleeping, sitting, light exercise and heavy exercise. To conduct the study, the particle size distributions of diesel and compressed natural gas (CNG) busses were monitored in field laboratory conditions. The study indicates that the total number of diesel particles measured is greater than the total number of CNG particles. The results further display that most of the diesel particles measured are smaller than 0.2 μm, whereas the CNG particles are smaller than 0.05 μm in aerodynamic diameter. The level of physical exercise, as well as the age and gender of a person affects the deposition of particles in the lungs. An increase in the physical activity results in larger amounts of small-size particles penetrating deeper into the respiratory system. The lung deposition of particles in males was substantially different compared to that of females and children. The deposited dose of particles was generally lower for females than for males and further lower for children than for females. This article argues that these groups should be discussed separately when conducting exposure assessments and that the level of physical activity should be taken into account when assessing potential health consequences.     

A microwatt switched-capacitor voltage doubler-based voltage regulator for ultra-low power energy harvesting systems

This paper presents an SC voltage doubler-based voltage regulator for ultra-low power energy harvesting applications. It produces a stable 1.2-V power supply, using inputs from 0.63 to 1.8 V. External compensation and an on-chip output capacitor ensure good performance even with zero load current and any load capacitance. The regulator tolerates arbitrary input ramp-ups, and is immune to blackout and brownout. A stability analysis for the regulator control loop is presented. The regulator ASIC is implemented in a 180 nm CMOS process. The measured regulator peak power and current efficiency are 63 and 49 %, respectively. The performance has been characterized with load currents from zero to \(100\,\upmu\)A.     

The influence of dairy salts on nanofiltration membrane charge

The nanofiltration of dairy ultrafiltration permeate can be used to produce a concentrated lactose product that is reduced in unwanted monovalent salts. In this paper, the surface charge of three nanofiltration membranes commonly used for such a purpose is examined. The focus is the impact of multivalent anions, notably phosphate and citrate, upon the surface charge of the membranes within a ternary system of potassium and calcium chloride. It was shown that these multivalent anions can influence the membrane charge through interactions with calcium, even though they are unlikely to adsorb to the membrane surface. Specifically, both phosphate and citrate can form soluble charged species with the calcium ions, reducing the net Ca²⁺ concentration and hence the overall effect of calcium on the membrane. This ion interaction effect becomes more dominant at higher pH values, due to the greater tendency of calcium to interact with either phosphate or citrate at higher pH.     

Listening to Brain Microcircuits for Interfacing With External World-Progress in Wireless Implantable Microelectronic Neuroengineering Devices: Experimental systems are described for electrical recording in the brain using multiple microelectrodes and short range implantable or wearable broadcasting units

Acquiring neural signals at high spatial and temporal resolution directly from brain microcircuits and decoding their activity to interpret commands and/or prior planning activity, such as motion of an arm or a leg, is a prime goal of modern neurotechnology. Its practical aims include assistive devices for subjects whose normal neural information pathways are not functioning due to physical damage or disease. On the fundamental side, researchers are striving to decipher the code of multiple neural microcircuits which collectively make up nature's amazing computing machine, the brain. By implanting biocompatible neural sensor probes directly into the brain, in the form of microelectrode arrays, it is now possible to extract information from interacting populations of neural cells with spatial and temporal resolution at the single cell level. With parallel advances in application of statistical and mathematical techniques tools for deciphering the neural code, extracted populations or correlated neurons, significant understanding has been achieved of those brain commands that control, e.g., the motion of an arm in a primate (monkey or a human subject). These developments are accelerating the work on neural prosthetics where brain derived signals may be employed to bypass, e.g., an injured spinal cord. One key element in achieving the goals for practical and versatile neural prostheses is the development of fully implantable wireless microelectronic "brain-interfaces" within the body, a point of special emphasis of this paper.     

Accounting for early action in the European Union Emission Trading Scheme

In the context of emission markets, failure to include early action (EA) as a criterion when sharing out the reduction effort may be unfair. This paper presents (1) a method based on index decomposition that seeks to quantify EA and (2) a method for determining effort sharing considering EA. It is shown that, in the case of European industry (EU-15) and for the period 1995–2005, EA accounted for a reduction of 21% in energy-related CO₂ emissions. Considering two alternative schemes for sharing out the reduction effort in European industry, equal shares (all industries in all countries reduce their emissions by the same percentage) and taking EA into account, we find that Spain, Austria, Italy, the United Kingdom and Sweden would be better off under an equal shares scheme as opposed to one that takes EA into account. The efforts of the remaining countries would be greater than if EA was taken into account. An equal shares scheme would also greatly benefit the textile, non-metallic mineral, paper and “other” industries, and would be particularly detrimental to the chemical, non-ferrous and other metal, and engineering industries.     

Forestry crane posture estimation with a two‐dimensional laser scanner

Crane posture estimation is the stepping stone to forest machine automation. Here, we introduce a robust minimal perception solution, that is, one that uses minimal constraints for maximal benefits. Specifically, we introduce a robust particle‐filter‐based method to estimate and track the posture of a flexible hydraulic crane by using only low‐cost equipment, namely, a two‐dimensional (2D) laser scanner, two short magnetically attached metal tubes as targets, and an angle sensor. An important feature of our method is that it incorporates control signals for hydraulic actuators. In contrast to the previous works employing laser scanners, we do not use the full shape of the crane to estimate the crane posture, but, instead, we use only two small targets in the field of view of the laser scanner. Thus, a large share of the range data is useful for other purposes, for example, to map the surrounding environment. We test the proposed method in a challenging forest environment and show that the particle filter is able to estimate the posture of the hydraulic crane efficiently and reliably in the presence of occlusions and obstructions. During our comprehensive testing, the tip position was measured with average errors smaller than 4.3 cm whereas the absolute maximum error was 15 cm.