Torque converter turbine noise and cavitation noise over varying speed ratio

These investigations will discuss the operational noise caused by automotive torque converters during speed ratio operation. Two specific cases of torque converter noise will be studied; cavitation, and a monotonic turbine induced noise. Cavitation occurs at or near stall, or zero turbine speed. The bubbles produced due to the extreme torques at low speed ratio operation, upon collapse, may cause a broadband noise that is unwanted by those who are occupying the vehicle as other portions of the vehicle drive train improve acoustically. Turbine induced noise, which occurs at high engine torque at around 0.5 speed ratio, is a narrow-band phenomenon that is audible to vehicle occupants currently. The solution to the turbine induced noise is known, however this study is to gain a better understanding of the mechanics behind this occurrence. The automated torque converter dynamometer test cell was utilized in these experiments to determine the effect of torque converter design parameters on the offset of cavitation and to employ the use a microwave telemetry system to directly measure pressures and structural motion on the turbine. Nearfield acoustics were used as a detection method for all phenomena while using a standardized speed ratio sweep test. Changes in filtered sound pressure levels enabled the ability to detect cavitation desinence. This, in turn, was utilized to determine the effects of various torque converter design parameters, including diameter, torus dimensions, and pump and stator blade designs on cavitation. The on turbine pressures and motion measured with the microwave telemetry were used to understand better the effects of a notched trailing edge turbine blade on the turbine induced noise.

Implementation of a Variable Compression Ratio Mechanism in a Four Cylinder Engine

Ever since the invention of the internal combustion engine, generating more power and achieving better efficiency has been a major goal for the designers. Variable compression ratio technology is way to achieve those goals. This paper will discuss the method of varying the compression ratio of an inline 4-cylinder engine through the use of a 4-bar linkage and gear mechanism. This mechanism was proven to easily vary the compression ratio of the engine and shows promise of becoming a technology used for future engine designer.

The Effect of the Cu:Fe''' Ratio Upon the Current Efficiency in the Electrolysis of a Copper Sulfate Solution Containing Iron Sulfate

It is a well-known fact that, in the electrolysis of a CuSO4 solution containing iron sulfate, using insoluble anodes, with the depletion of copper, the point is finally reached where the current efficiency becomes zero. This decrease in current efficiency is due to the oxidation of the ferrous sulfate to the ferric condition at the anode, by the oxygen liberated. The resulting ferric sulfate diffuses over to the cathode and there dissolves copper from the cathode according to the chemical equation Cu + Fe2 (SO4)3 = CuSO4 + 2FeSO4. This copper, which has been deposited at the cathode by the electric current, is thus redissolved by the Fe2(SO4)3. The solution of the copper causes at the same time a formation of FeSO4 which in turn diffuses over to the anode and is there oxidized to Fe2(SO4)3; and so the cycle continues, using electric current without rendering useful work. E. H. Larison has noted that a definite amount of ferric salts must be reduced to the ferrous condition before all the copper will remain on the cathode; he does not state, however, just what this point is. L. Addicks has plotted the relation between current efficiency and ferric sulphate content. The existence of the results scattered the points more or less, although the decrease in current efficiency with increased ferric sulphate content is clearly indicated. E. T.Kern has likewise noted that the smaller the amount of copper in the solution, the greater is the reduction of current efficiency. In this work, therefore, it was desired to determine what amount of ferric iron was permissible in a copper sulfate solution of definite concentration before the current efficiency would drop to zero, and what, if any, was the effect of definite Cu:Fe’’’ratio upon the current efficiency of the electrolysis.

The Effect of the Fe2: Fe3 Ratio upon the Current Efficiency in the Electrolysis of a Copper Sulfate Solution Containing Iron Sulfate

In the treatment of copper ores by hydro-electro-metallurgical methods, not only is copper deposited, but other metals are also dissolved. In practice it has been found* that iron, under certain conditions, causes the copper to deposit on the cathode as a nonadherent precipitate and also that the iron in solution causes a great decrease in current efficiency, es­pecially when the electrolysis is conducted by operating with a higher current density at the cathode than at the anode. The present investigation deals with the effects of the two valences of iron on the current efficiency and endeavors to determine whether or not there is a ratio of the two at which point the efficiency becomes zero or approaches it.

Applications of Stable Isotope Ratio Analysis for Social Science Research

Stable Isotope Ratio Analysis (SIRA) is the measurement of variation in different isotopes of same elements in a material. This technique is well-established in the natural sciences and has been long part of the methodological arsenal in fields such as geology and biology. More recently this technique has begun to be utilized in the social sciences, moving from initial applications in anthropology to potential uses in geography, public health, forensic science, and others. This presentation will discuss the techniques behind SIRA, examples of current applications in the natural and social sciences, and potential avenues of future research.

Differential effects of anti-hypertensive treatment on the retinal microcirculation: an Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) sub- study

Changes in the retinal microcirculation are associated with hypertension and predict cardiovascular mortality. There are few data describing the impact of antihypertensive therapy on retinal vascular changes. This substudy of the Anglo-Scandinavian Cardiac Outcomes Trial compared the effects of an amlodipine-based regimen (373 patients) with an atenolol-based regimen (347 patients) on retinal microvascular measurements made from fundus photographs. The retinal photographs were taken at a stage in the trial when treatments were stable and blood pressure was well controlled. Amlodipine-based treatment was associated with a smaller arteriolar length:diameter ratio than atenolol-based treatment (13.32 [10.75 to 16.04] versus 14.12 [11.27 to 17.81], median [interquartile range]; P<0.01). The association remained significant after adjustment for age, sex, cholesterol, systolic and diastolic blood pressures, body mass index, smoking, and statin treatment. This effect appeared to be largely attributable to shorter retinal arteriolar segment lengths in the amlodipine-treated group and is best explained by the vasodilator effects of amlodipine causing the visible emergence of branching side vessels. Photographic assessment of the retinal vascular network may be a useful approach to evaluating microvascular structural responses in clinical trials of antihypertensive therapy.

Automatic Labeling of Software Components and their Evolution using Log-Likelihood Ratio of Word Frequencies in Source Code

As more and more open-source software components become available on the internet we need automatic ways to label and compare them. For example, a developer who searches for reusable software must be able to quickly gain an understanding of retrieved components. This understanding cannot be gained at the level of source code due to the semantic gap between source code and the domain model. In this paper we present a lexical approach that uses the log-likelihood ratios of word frequencies to automatically provide labels for software components. We present a prototype implementation of our labeling/comparison algorithm and provide examples of its application. In particular, we apply the approach to detect trends in the evolution of a software system.