A 12.5 Gb/s Si bipolar IC for PRBS generation and bit errordetection up to 25 Gb/s

This paper describes a Si bipolar IC which features PRBS generation, bit error detection, (de-) scrambling, and trigger derivation up to 12.5 Gb/s. The sequence length is switchable between 2 ¹¹-1 and 2¹⁵-1 b. Two input/output channels are provided which allow PRBS testing up to 25 Gb/s with one external MUX/DMUX. The 3×4 mm², 1377 transistor chip uses 0.4 μm emitter 25-GHz-f_T single-poly self-aligned Si bipolar technology and dissipates 4.6 W from a single -5 V supply     

Open fires: Experiments and theory

The open fire is used by millions of households around the world to perform a variety of tasks, the principal one being that of cooking in third world countries. Its virtues are simplicity of design and nearly zero cost. In this study we use it as a convenient tool for investigating certain general characteristics of woodburning stoves for cooking. The paper is in three parts. The first part delineates the influence of fuel, operating and design characteristics of open fires on the efficiency as determined by water boiling tests. The second part provides an insight into certain physical characteristics of wood-fires through instantaneous weight-loss measurements. In particular this part helps to explain the results of the first part. The final part provides anad hoc theoretical model which enables the calculation of radiant and convective heat transfer to a pan placed on an open fire. The theoretical calculations compare favourably with experimental results.     

The temperature dependence of the isotope effect for self-diffusion and cobalt impurity-diffusion in gold

Measurements of the self-diffusion and the isotope effect of ¹⁹⁵Au and ¹⁹⁹Au in gold as well as the isotope effect of ⁵⁷Co and ⁶⁰Co impurity-diffusion in gold are reported. A significant decrease of both types of isotope effects with increasing temperature is observed, which is attributed to a divacancy contribution to the total diffusion rate. At 1323 K $\text{D}{}^1{}_{\mathrm{2v}}\text{D}{}^1\text{? 0.2}$ is deduced. This result is supported by the small curvature near T_m of the Arrhenius plot of the self-diffusion data. For cobalt impurity-diffusion via divacancies an isotope effect $\text{E}{}_{\mathrm{2v}}{}^{\mathrm{Co}}\text{? 0.3}$ is estimated at T_m. Assuming the validity of the jump frequency model for impurity-diffusion in fcc metals it is concluded from additional isotope effect experiments of Co in Cu and Au in Cu, that the mass dependence of the ΔK factor should be very small.     

Angiography of left ventricle following volume load and physical work in coronary disease

In order to recognize and quantitate abnormalities in wall segment motion in 22 patients simultaneous measurements of isovolumic and ejection phase parameters were performed with the Millar-angiographic catheter at rest, after leg raising and during bicycle exercise. 6 patients had slight coronary heart disease (CHD) (group I), 16 patients had severe CHD (group II). During volume load in all patients of gr. II a decrease of peak measured velocity (Vpm) and the velocity of circumferential fiber shortening (Vcf from 1.4 to 1.1 circ/s, p less than 0.025) occurred. In gr. I Vcf increased (p less than 0.05). During exercise there was a high increase in Vpm and Vcf in gr. I (from 1.2 to 1.9 circ/s) whereas in gr. II no increase was observed. LVEDP rose to 29 mm Hg and ESV from 58 to 70 ml/1.73 m2. By increasing LVEDP during volume load underperfused areas became ischaemic and akinetic. During physical work the segmental abnormality can be less pronounced possibly due to the higher prestenotic pressure.     

Milk lactoferrin in heifers: Influence of health status and stage of lactation

The objective of the current study was to analyze the variations in lactoferrin (LF) concentrations in primiparous cows with intramammary infection and to study how the lactation stage affects these variations. In addition, we aimed to study the potential of the LF concentration in early lactation as a predictive factor for future infections. To accomplish this goal, a longitudinal analysis was performed for 96 primiparous cows. Milk samples were collected each month from individual quarters, and the LF concentration was determined for each sample. Criteria that included both somatic cell count (SCC) and a microbiological analysis were used to assess the health status of the quarters. Of the diseased quarters (SCC >200,000 or positive for pathogen isolation, or both), 62% corresponded to nonspecific mastitis (SCC >200,000 but microbiologically negative) and 25% corresponded to the category “presence of bacterial growth” (SCC <200,000 but microbiologically positive). Diseased quarters showed increased concentrations of LF compared with healthy quarters. However, this increase was greater during the first days of lactation compared with later periods. Kaplan-Meier analysis of time free of infection demonstrated that quarters with LF concentrations at early lactation (3–10 d in milk) greater than 0.1 mg/mL are more likely to become infected during the following lactation compared with quarters with lower LF concentrations in early lactation. The results support that LF plays a relevant role in combating intramammary infection, particularly during the first days of lactation. In addition, we present evidence of the potential use of LF as a predictive marker of future infections in the individual quarters of dairy heifers.     

Aluminium scrap melting under different liquid aluminium flow conditions: part-I: single phase flow

The melting characteristics of aluminium (Al) scrap were studied in a pilot-scale revolving liquid metal tank (RLMT) which sits in a resistance furnace. Commercially pure Al of about 39?kg was melted in the RLMT. Experiments were carried out in a stagnant and in a revolving Al bath at different liquid metal temperatures and speeds. Cylindrical Al 6061 alloy samples were used in this experimental work. Their melting time inside the Al bath was recorded with a specially designed electrical circuit. Upon immersion of a cold cylindrical sample into liquid Al, a shell solidifies around the specimen and subsequently melts back. The time during which the shell exists around the cylinder is called shell period. The free melting period commences when the shell period ends. The thermal contact resistance (TCR) at the Al shell/cylinder interface affects how long the shell lasts. A methodology was developed to estimate this TCR. The convective heat flux from the Al bath to the cylindrical specimen influences the shell and free melting periods, and is a function of liquid Al temperature and speed. The Part I of this research work presents a baseline of Al melting measurements under single phase flow conditions, that will be compared against two phase flow conditions in Part II of this research.

On a étudié les caractéristiques de fusion de rebut d’aluminium (Al) à l’échelle pilote dans une citerne rotative de métal liquide (RLMT), située dans un four à résistance. On a fait fondre dans la RLMT environ 39?kg d’Al commercialement pur. On a effectué les expériences dans un bain stagnant ou dans un bain rotatif d’Al à diverses températures et à diverses vitesses du métal liquide. Dans ce travail expérimental, on a utilisé des échantillons cylindriques d’alliage d’Al 6061. On a enregistré leur temps de fusion dans le bain d’Al au moyen d’un circuit électrique spécialement conçu. Au moment de l’immersion d’un échantillon cylindrique froid dans l’Al liquide, une coquille se solidifie autour de l’échantillon et subséquemment, fond à son tour. La période durant laquelle la coquille existe autour du cylindre s'appelle la période de coquille. La période de fonte libre commence quand la période de coquille se termine. La résistance du contact thermique à l’interface coquille et cylindre d’Al affecte la durée de vie de la coquille. On a développé une méthodologie pour estimer cette résistance du contact thermique. Le flux de chaleur par convection du bain d’Al à l’échantillon cylindrique influence les périodes de coquille et de fonte libre, et il est une fonction de la température et de la vitesse de l’Al liquide. La première partie de ce travail de recherche présente une ligne de base des mesures de fusion de l’Al sous des conditions d’écoulement monophasé, qui sera comparée à des conditions d’écoulement biphasé dans la deuxième partie.     

Doping of graphene exfoliated on SrTiO3

We present atomic force microscopy and scanning Kelvin probe data obtained under ultra-high vacuum conditions from graphene exfoliated on crystalline SrTiO(3) substrates. The contact potential difference shows a monotonic increase with the number of graphene layers until after five layers of saturation is reached. By identifying the saturation value with the work function of graphite we determine the work function of single and bilayer graphene to be Φ(SLG) = 4.409 ± 0.039 eV and Φ(BLG) = 4.516 ± 0.035 eV, respectively. In agreement with the higher work function of single-layer graphene with respect to free-standing graphene, our measurements indicate an accumulation of charge carriers corresponding to a doping of the exfoliated graphene layer with electrons.     

Whole-body impedance control of wheeled mobile manipulators

Humanoid service robots in domestic environments have to interact with humans and their surroundings in a safe and reliable way. One way to manage that is to equip the robotic systems with force-torque sensors to realize a physically compliant whole-body behavior via impedance control. To provide mobility, such robots often have wheeled platforms. The main advantage is that no balancing effort has to be made compared to legged humanoids. However, the nonholonomy of most wheeled systems prohibits the direct implementation of impedance control due to kinematic rolling constraints that must be taken into account in modeling and control. In this paper we design a whole-body impedance controller for such a robot, which employs an admittance interface to the kinematically controlled mobile platform. The upper body impedance control law, the platform admittance interface, and the compensation of dynamic couplings between both subsystems yield a passive closed loop. The convergence of the state to an invariant set is shown. To prove asymptotic stability in the case of redundancy, priority-based approaches can be employed. In principle, the presented approach is the extension of the well-known and established impedance controller to mobile robots. Experimental validations are performed on the humanoid robot Rollin’ Justin. The method is suitable for compliant manipulation tasks with low-dimensional planning in the task space.     

Chaotic Shape and Translational Dynamics of 2D Incompressible Bubbles under Forced Vibration in Microgravity

Nonlinear shape oscillations of 2D incompressible bubbles in an inviscid fluid, subject to a forced vibration in microgravity, have been studied numerically. Forced vibration induces an oscillatory translational motion as well as shape oscillations. It is shown that for large enough oscillation amplitudes, the coupling between the shape oscillation and the translational motion of a bubble results in a chaotic behaviour. For two-bubble systems, the bubbles may attract each other. The attraction force is stronger at higher Bond numbers. Higher Bond numbers also yield larger bubble deformation.     

Breakup of brittle deposits by supersonic air jet: The effects of varying jet and deposit characteristics

The breakup by supersonic air jet of cylindrical brittle gypsum deposits formed on tube surfaces was studied using high-speed imaging. The breakup of symmetric deposits was visualized from the front and back simultaneously, and the effects of deposit asymmetry, jet/deposit attack angle, and jet duration and frequency, were investigated. Three jet types were considered: short and long duration single pulses, and a pulsating jet. For each experiment, the time to breakup, the breakup duration, and the breakup length were measured. Results indicate that the breakup of asymmetric deposits depends on orientation, and that attack angle affects the probability of breakup and breakup length. Results also indicate that soft deposits can be broken by any jet type, while harder deposits, especially those farther from the nozzle exit, require a longer exposure time to be broken. Pulsating jets do not improve breakup effectiveness. This work has relevance to cleaning of fireside deposits formed on heat exchanger tubes in boilers.