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An apparatus for studies of wire explosions in air at atmospheric as well as reduced pressures is described. A theoretical treatment of the discharge circuit is presented. In this treatment the external resistance and inductance as well as the wire inductance (all as functions of time) have been taken into consideration. It is then possible to calculate the wire variables — current, resistance, resistive voltage drop, effect, and energy input — as functions of time from thedI/dt waveform experimentally obtained. Wire variables of Ni- and W-wires exploded both in air and vacuum are presented as well as a discussion of these.

A new electrolytic selenium photo‐cell is described and its characteristics given as a function of operating voltage, temperature, external resistance, and time. Data are included indicative of its response to unmodulated, modulated, and monochromatic light; comparison is made with cells of similar type or possessing similar characteristics; and a method of compensating for the dark current of photo‐cells is shown.An electronic circuit is also described which can greatly improve the voltage output of the photo‐element. It is generally applicable to photo‐conductive and photo‐voltaic cells.

A simple model of the energy flows about a leaf yields new expressions for the temperature, external diffusion resistance, internal diffusion resistance, and the transpiration rate. The effects are considered of either (i) coating the leaf to make its surface impermeable to water vapour, or (ii) wetting the leaf surface, or (iii) shading it. As a result, four methods of deriving a leaf's external resistance and four for determining the transpiration rate have been deduced, and compared using data from field measurements on intact vine leaves. The results obtained by the various methods are roughly similar, but anomalies need further investigation.

A dynamic method of finding ∂2i g /∂e g 2or ∂k g /∂e g , the main term in grid-circuit rectification, is given. This method is based upon formulas given by Chaffee and Browning and consists in calculating ∂k g /∂e g from the change of d.c. when a known a.c. input voltage is applied to the grid. The values of ∂k g /∂e g found by the dynamic method are compared with the values found by the usual method. The effect of frequency, internal grid resistance, and external resistance on the detection voltage introduced in the plate circuit are also considered. An experimentally determined curve is given showing the detector frequency distortion of a commercial set for a 2-megohm grid leak and for a ½-megohm grid leak.

Tolerance of additional external resistance to inspiration has been investigated in 158 mine rescue workers during exercise. Peak inspiratory pressure, minute volume, and respiratory work rates were calculated in order to determine which factor best correlated with subjective tolerance of resistance. A method of defining an acceptable limit for inspiratory resistance is presented, which considers the additional respiratory work load in terms of unit ventilation. St is concluded that excessive pressure exerted during inspiration is a major factor in determining subjective tolerance. It is suggested that 90% of a population breathing through apparatus with low-resistance expiratory valves should experience no discomfort, if the pressure across the apparatus does not exceed 17 cm H2O.

Furusawa, Hill and Parkinson (1) have shown that the acceleration of a runner and the maximum speed he can obtain depend upon two factors, ( a ) the maximum force he can exert in propelling himself, and ( b ) the frictional resistance of his muscles. They have experiment these factors in a mathematical equation, which they have tested by experiment. The experimental results fit the equation very satisfactory and allow the values of the constants to be determined. The maximum velocity attained depends upon a balance between the propelling force, which is constant up to the onset of fatigue, and the internal resistance, which increases as the speed rises until it balances the propelling force. In spite of the accuracy with which experiment has been found to verify the equation, this internal resistance has to some degree a hypothetical existence. The object of the present paper is to give it greater reality by showing how an actual external resistance can be added on to it and produces exactly the calculated effect.

Summary Two expressions as shown by eqns. (1) and (3) are postulated and verified experimentally for the dependencies of the HF polarographic wave height, i HF , on the depolarizer concentration C , the amplitude Δ E HF of the HF pulse, and the external resistance R ext . The statistical analysis of data has shown that eqn. (3) holds more accurately than eqn. (1) (see Table 3). The importance of lowering the circuit resistance in HF polarography is emphasized.

The extraction of lanthanum and barium from single falling drops of the uranium-chromium eutectic into magnesium was studied at 1,000°C. Because of the short contact times involved, the data best fit the stagnant diffusion model for lanthanum. For barium, the fraction extracted was governed by external resistance of the magnesium phase. Drop velocities were adequately represented by the Hu-Kintner correlation.

Simultaneous electricity generation and combined carbon and nitrogen removal in wastewater using microbial fuel cells are an intriguing process. The generation of electricity from nitrogen-rich wastewater was examined using single chamber air cathode microbial fuel cells (SCMFCs). SCMFCs were fed with an artificial wastewater containing the initial chemical oxygen demand (COD): total nitrogen (N) ratio of 2.5:1.0, and operated under mesophilic batch mode. The power density increased with increasing wastewater concentration. Performance of SCMFCs with external resistances, 500 and 1,000 Ω, based on maximum power density and current was compared. The SCMFCs with 500 Ω gained higher maximum power density and current output by 12.5 and 23.3%, respectively, compared to 1,000 Ω. The COD and ammonium removal in 500 Ω condition was 81 and 98%, respectively. The findings suggested that MFC is a potential technology to treat carbon and nitrogen pollutants in wastewater, and recover electric energy at the same time.

IT HAS been accepted generally that the waves of bending observed in swimming vertebrates are produced by contraction on the concave side of each bend of the body at any point within the cycle of movement1–3. “Waves of contraction” are imagined to pass down the serial mytomes with the velocity of the propagated bends. Another concept, designed primarily to explain snake locomotion4, differs by a 90° shift in the timing of contraction on the bending wave, accounting for propulsion but resulting in illogical analysis of fish movement5. The former interpretation gives no explanation of the source of locomotory thrust, assuming falsely that the muscular activity required for a given body position is similar whether the position is held or passed through in locomotion. The dominant responsibility of locomotory activity is the propagation rather than the formation of bends, but how is propagation achieved against external resistance? Relevant electromyography of spinal dogfish6,7 has not been related to this mechanical problem. I present here a preliminary report of electromyographic studies of developmental stages of the palmate newt, Triturus helveticus (Razoumowsky), and adult tench, Tinca tinca L., which show that undulatory propulsion in some animals does not involve waves of contraction and that the “waves” recorded in others function in reducing lateral oscillation anteriorly and adapting tail flexibility to different swimming speeds.

The dependence of the frequency and other parameters of moving striations in low pressure gas discharge on the magnitude and kind of external limiting element was studied. The experimental conditions are described. The results show that the magnitude of the external limiting ohmic resistance affects the amplitude of light intensity oscillation of the moving striations and its speed and wavelength. However, the frequency is not affected. The frequency is affected by the presence of the inductive part of external limiting element. (J.S.R.)

A new type of pump is described which has the unique property of being able to move a fluid without change in pressure, volume, or temperature. Against a small external resistance, it can be used for pressure, vacuum, or circulation of a gas, and with a simple attachment, liquids may be pumped.

The biomechanics of the foot and ankle are important to the normal function of the lower extremity. The foot is the terminal joint in the lower kinetic chain that opposes external resistance. Proper arthrokinematic movement within the foot and ankle influences the ability of the lower limb to attenuate the forces of weightbearing. It is important for the lower extremity to distribute and dissipate compressive, tensile, shearing, and rotatory forces during the stance phase of gait. Inadequate distribution of these forces could lead to abnormal stress and the eventual breakdown of connective tissue and muscle. The combined effect of muscle, bone, ligaments, and normal foot biomechanics will result in the most efficient force attenuation in the lower limb. This article will look specifically at the normal biomechanics of the foot and ankle. J Orthop Sports Phys They 1985;7(3):91-95.

Using the Scholander-Hammel pressure-bomb it is possible to measure the kinetics of water exchange between the shoot and a suitable collecting vial in response to a rapid water potential change (= pressure increment), and by measuring the kinetics under different experimental conditions, it is possible to build up a quantitative picture of the magnitude and location of the major resistances to bulk water flow within woody shoots. This paper reports our continuing efforts to measure and locate the resistances to bulk water flow in the shoots of eastern hemlock (Tsuga canadensis)

The practical applications and limitations of four methods for extracting the effective channel length (L/sub eff/) and series resistance (R/sub ext/) parameters for MOS devices are studied. The methods are: GD (gate drive) using fixed-current V/sub t/ or GD(I/sub ds/); SBGD (substrate-bias GD) using fixed-current V/sub t/ or SBGD (I/sub ds/); GD using maximum slope V/sub t/ or GD (G/sub m/); and SBGD using maximum slope V/sub t/ or SBGD (G/sub m/). Conventional and two LDD (lightly doped drain) structures fabricated in a submicrometer CMOS process are used. The results indicate that all the extraction methods are applicable to both n-channel and p-channel devices, although some are only valid over a small range of gate biases. Inconsistencies in applying V/sub t/ calculations to the extraction equations set a lower limit for V/sub gst/ of approximately 0.5 V, while the upper limit of 2.0-4.0 V arises due to imprecision in R/sub ds/ measurements influencing the double regression steps involved in the techniques. The SBGD (I/sub ds/) method was applicable over a wider range of bias conditions than the other techniques analyzed and is easier to implement. >

Unsteady-state flow occurs when the flux and gradient are variable in both space and time. Such flow has more importance in wood treatments than steady-state flow, since it is present whenever a wood specimen is heated, evacuated, impregnated with liquids, or dried. In all these cases there is a net change in the conditions inside the specimen over a period of time.

We examined the effects of varying inspiratory pressures and flows on inspiratory muscle endurance. Four normal subjects performed voluntary forced breathing with various assigned inspiratory tasks. Duty cycle, tidal volume, and mean lung volume were the same in all tasks. Mean esophageal pressure, analogous to a pressure-time integral (PTes), was varied over a wide range. In each task the subject maintained an assigned PTes while breathing on one of a range of inspiratory resistors, and this gave a range of inspiratory flows at any given PTes. Inspiratory muscle endurance for each task was assessed by the length of time the task could be maintained (Tlim). For a given resistor, Tlim increased as PTes decreased. At a given PTes, Tlim increased as the external resistance increased and therefore as mean inspiratory flow rate (VI) decreased. Furthermore, for a given Tlim, PTes and VI were linearly related with a negative slope. We conclude that inspiratory flow, probably because of its relationship to the velocity of muscle shortening, is an independent variable importantly influencing endurance of the inspiratory muscles.

The rate of external work done against the resistance of a respiratory circuit was measured from pressure-volume diagrams. Eight subjects breathed through the circuit at many levels of exertion. At any given minute volume the rates of external respiratory work were similar for all subjects. The circuit was also ventilated by a sine-wave pump at corresponding minute volumes. The rate of work done by the pump at all minute volumes corresponding to exercising men was also similar. It was, therefore, concluded that in estimations of the rate of respiratory work on exercise, it is justifiable to assume that the human respiratory wave behaves as a sine wave.

1. It was confirmed that normal subjects can detect an increase in airways resistance of 1.2 cmH2O 1−1 s when this is presented during a sequence of otherwise unresisted breaths. 2. In contrast when such subjects meet the same resistance presented unexpectedly during a sequence of breaths against a larger resistance (2.5 cmH2O 1−1 s), they commonly fail to detect it, indicating that they believe no external resistance remains. 3. Subjects breathing continuously against a given external resistance frequently during the course of the study indicate that they believe that a decrease in resistance has been made.

The outgassing characteristics of specimens of the EGCR moderator graphite stock were determined in vacuo to a maximum temperature of 1000 deg C using external resistance heating and to 1800 deg C by induction heating. The specimens examined were cut from several locations in two of the 18-in. x 18-in. x 20-ft graphite bars which had been prepared under fabrication conditions comparable to those used for the graphite columns present in the Experimental Gas- Cooled Reactor. Data are given which show the effect of the position of sampling of the bars on the density of the graphite. The volume and composition of desorbates obtained at 300, 600, and 1000 deg C as a function of specimen size and position of specimen within the bars also are given. The volume-time relationships at 300 and 600 deg C can be expressed satisfactorily by v = A log t + B over extended intervals of time. A linear relationship prevails at 1000 deg C only after heating for longer than approximates 800 min. The volume and composition of the desorbates obtained at 1000, 1400, and 1800 deg C using induction heating are tabulated. (auth)

Appropriate inoculation and maturation may be crucial for shortening the startup time and maximising power output of Microbial Fuel Cells (MFCs), whilst ensuring stable operation. In this study we explore the relationship between electrochemical parameters of MFCs matured under different external resistance (Rext) values (50 Ω - 10 kΩ) using non-synthetic fuel (human urine). Maturing the biofilm under the lower selected Rext results in improved power performance and lowest internal resistance (Rint), whereas using higher Rext results in increased ohmic losses and inferior performance. When the optimal load is applied to the MFCs following maturity, dependence of microbial activity on original Rext values does not change, suggesting an irreversible effect on the biofilm, within the timeframe of the reported experiments. Biofilm microarchitecture is affected by Rext and plays an important role in MFC efficiency. Presence of water channels, EPS and precipitated salts is distinctive for higher Rext and open circuit MFCs. Correlation analysis reveals that the biofilm changes most dynamically in the first 5 weeks of operation and that fixed Rext lefts an electrochemical effect on biofilm performance. Therefore, the initial conditions of the biofilm development can affect its long-term structure, properties and activity.

A pulsed-waveguide CO 2 laser is described for which no electronic pulser is required because the discharge properties of the waveguide laser and the external resistance and capacitance form a relaxation oscillator. Peak powers of 15 W were obtained at repetition rates up to 20 kHz for the 10-cm discharge.

The longitudinal internal as well as external resistance was measured by means of simultaneous intracellular and sucrose gap voltage recordings. The longitudinal internal resistance could be calculated from a formula comprising the shunt resistance, membrane action potential and transgap action potential before and after shunting. The longitudinal external resistance was calculated from another formula comprising the same quantities.

A simple high‐temperature pressure‐vacuum furnace using a recrystallized alumina tube as the vessel with external resistance windings is described. Temperatures to 1900°C can be used in both strongly reducing and oxidizing atmospheres. Pressures to 28 atoms at 1200°C were obtained and no water cooling was required. Differential thermal analysis with continuous gas analysis of reaction products is made possible.

A small still, made from heat-resisting glass, for the fractionation of about 20 ml. of liquid, is described. It comprises a fractionating column 6 in. long and I in. bore packed with in. gauze rings and sealed to a boiler which is fined wih an external resistance heater. The column, when tested ushg a mixture of normal heptane-methyl Eyclohcxanc, has a performance equivatent to about 12 theoretical plates at a vaspour veiocity of 0.8 ft. per second, the dynamic liquid hold-up is approximately I ml. and the static hold-up is 0.1 ml. The sull may be used at atmospheric pressure to fractionate material boiling up. to 250°c. and, because of the low pressure drop, it is very suitable also for fractionation at reduced pressure.

The frequency dependence of A.C. conductance of organic solid thin films have been discussed. It is pointed out that the dependence of conductance on the square of frequency is an artifact due to the electrode contact resistance and the capacity of the film. In this paper a method of an added external resistance is proposed to evaluate the electrode contact resistance and thereby the experimentally measured frequency dependences of conductance and capacity of the film could be corrected for the effect of electrode contact resistance. In order to characterize the A.C. conductance of organic solid thin films three parameters are suggested. That is, the D.C. specific conductance σd.c. at extremely low frequencies, the exponent n in the expression σ(f)∝fn for the region of higher frequencies and the value of fx at which the straight line on the lgσ-lgf plot intersects the horizontal line σ=σd.c. For a solution cast film of poly-vinylcarbazole (PVK)-2,4,7-trinitrofluorenone (TNF) (1:0.75) charge transfer complex and an evaporated film of copper phthalocyanine (PcCu) the following results were obtained:PVK-TNF(1:0.75):σd.c.=1.9·10-16(Ω·cm)-1,n=0.96,fx=6.1·10-3Hz at 14℃, PcCu: σd.c.=1.6·10-9(Ω·cm)-1,n=1.2,fx=1·105Hz at 17℃.

The normal method used to measure the temperature of the windings of transformers, reactors and other heavy electrical plant is by change of resistance. Resistances are measured before and after the heat run by simple d.c. measurements. Using the known temperature coefficients of resistance for copper, the temperature at shut-down is calculated. It is shown that inductance causes errors, leading to apparently higher temperatures than actually exist. The errors become increasingly serious the larger the unit under consideration. The inductive effects are examined by means of analysis and digital computer, when it is shown that controlling factors are the electrical and thermal time-constants of the winding. Ameliorative measures are suggested. It is important to include external resistance in series with the test winding so as to lower the electrical time-constant. The test current must be sufficient to saturate the core of the magnetic circuit. Though mainly applicable to transformers, the conclusions are relevant to any heavy winding.

An explanation is given of the oscillations of current at constant external potential which are found in different electrode processes; this is based on the external resistance, the negative slope in the current potential curve, and the concentration polarization. A mathematical model, consisting of simplified expressions for these three properties, and an electronic analogue circuit show waveform and frequency dependence in agreement with experiments.