频率不受运放参数影响的文氏桥振荡器

本文介绍一组（12个）新的正弦振荡器，这组振荡器使用两个运算放大器，其振荡频率不受单极点有源元件增益带宽之积的影响。这种特性是由本文所介绍的电路结构取得的，即不需要调节。     

Where have all the traditional classroom settings gone?—The use of large scale, public sector projects to illustrate a multidisciplinary approach to problem solving

This work describes the evolution and potential of an elective course for students who have already been exposed to the standard techniques of problem solving as presented in traditional courses. Students apply these techniques to large scale problems in directed mullidisciplinary project teams. In doing so, they are provided with a unique learning experience allowing them to serve as a resource to the community. Course projects described here include the promotion of a railing retail district; the formulation, implementation and monitoring of litter reduction strategies; the economic evaluation of using inmate labor to clean public areas; and economic comparisons of recycling strategies for used tires.     

Asymptotically optimal estimation of smooth functionals for interval censoring, part 1

Estimation in the interval censoring model is considered. A class of smooth functionals is introduced, of which the mean is an example. The asymptotic information lower bound for such functionals can be represented as an inner product of two functions. In case 1, i.e. one observation time per unobservable event time, both functions can be given explicitly. We mainly consider case 2, with two observation times for each unobservable event time, in the situation that the observation times can not become arbitrarily close to each other. For case 2, one of the functions in the inner product can only be given implicitly as solution to a Fredholm integral equation. We study properties of this solution and, in a sequel to this paper, prove that the nonparametric maximum likelihood estimator of the functional asymptotically reaches the information lower bound.     

What Can Be Learned from DuPont and the Freon Ban: A Case Study

Between 1974 and 1988, executives of DuPont, the world's largest producer of CFCs, were confronted with emerging evidence that CFCs were destroying the stratospheric ozone layer. The difficulty that executives face in such cases is that scientific knowledge develops over time and does not necessarily proceed in a straight line toward true conclusions. At the beginning of a new field of research, there is much uncertainty and disagreement among the experts. The solution of the ozone problem required a remarkable cooperation among science, business, and international governments. After looking at the role of DuPont executives in this drama, and the difficulties facing any executive dealing with uncertain science, the paper turns to an evaluation of the field of Business Ethics to see what light it might throw on this and analogous problems. Finally, the paper offers specific suggestions in terms of principles in dealing with uncertain science, and concludes that the course of action that DuPont followed, including some mistakes, can serve as a model for analogous crises.     

UNIVERSAL BANKS ARE NOT THE ANSWER TO AMERICA'S CORPORATE GOVERNANCE "PROBLEM": A LOOK AT GERMANY, JAPAN, AND THE U.S.

This article objects to a recent tendency of legal and economic scholars to "romanticize" the corporate governance role of German universal banks and Japanese main banks. There are potential conflicts between banks' interests as lenders and as shareholders that are likely to make banks less-than-ideal monitors for outside shareholders. Citing evidence that Japanese corporate borrowers pay above-market interest rates for their bank financing, Macey and Miller interpret the high interest rates as "rents" earned by Japanese banks on their loan portfolios in exchange for (1) insulating incumbent management of borrower firms from hostile takeover and (2) accepting suboptimal returns on their equity holdings.
The main problems with the German and Japanese systems stem from their failure to produce well-developed capital markets. Concentrated and stable shareholdings reduce the order flow in the market, thereby depriving the market of liquidity. And the lack of capital market liquidity– combined with the intense loyalty of the banks towards incumbent management–removes the ability of outside shareholders to make a credible threat of takeover if managerial performance is substandard.
The problem with American corporate governance–if indeed there is one–is not that hostile takeovers are bad, but that there are not enough of them due to regulatory restrictions and misguided legal policies. While U.S. law should be amended to give banks and other debtholders more power over borrowers in the case of financial distress, encouraging U.S. banks to become large stockholders is not likely to improve corporate efficiency. Strengthening the "voice" of American equity holders by eliminating restrictions on the market for corporate control would be the most effective step in improving firm performance.     

Risk Management by Securities Settlement Agents

As developing countries search for ways to promote capital formation through the establishment of organized exchanges, they will need to pay more attention to the role of risk management in the securities settlement process. The delivery-versus-payment (DVP) agents that facilitate the process of exchanging securities for funds in most world markets have both the incentive and comparative informational advantage to monitor, measure, and manage risks inherent in the securities settlement system.
Unfortunately, most DVP agents have accomplished this task to date through the cumbersome use of position and net debit limits, capital requirements, and collateral requirements. Such limits and requirements are almost everywhere based on relatively arbitrary criteria that may have no relation to the actual replacement cost, principal, or liquidity risk of the transaction, portfolio, or participant on which they are imposed.
To remedy this shortcoming in the current state of risk management at DVP agents, this article holds out the possibility of integrated, comprehensive risk management processes that emphasize and rely on forward-looking measures of risk for individual brokers and across brokers. Many risk measures could serve the settlement agent's purposes, including "value at risk" (or "VaR"), "below target risk,""below-target probability," and "downside semi-variance." The actual summary risk measure used for risk monitoring and control is not as important as the methodology used to generate that risk measure. "The goal of such a process," as the authors put it, "is to ensure that the risks to which a settlement agent and its residual claimants are exposed are those risks to which the agent's shareholders think they are and want to be exposed."     

The Robustness of the APT to Alternative Estimators

We test the robustness of the APT to two alternative estimation procedures: the Fama and MacBeth (1973) two-step methodology; and the one-step procedure due to Burmeister and McElroy (1988). We find that the APT is indeed sensitive to the chosen estimator and assumptions about the factor structure of stock returns. We believe that our findings have implications for the estimation of asset pricing models in general.     

SOME ANALYTICS OF WHY CONDITIONAL IRRs CAN CONTAIN GROWTH RATE RELATED MEASUREMENT ERROR

This paper investigates the consequences of incorrectly modelling the investment outflow/benefit inflow relationship on estimates of the internal rate of return (IRR) prepared by using cash recovery rates (CRRs). The main result of this paper is that CRR-based estimates of the IRR will contain such bias if and only if either the duration of the assumed shape of the investment outflow/benefit inflow relationship is less than the duration of the true investment outflow/benefit inflow relationship for all rates of interest or the duration of the assumed shape of the investment outflowlbenefit inflow relationship is greater than the duration of the true investment outflowlbenefit inflow relationship for all rates of interest. This result is then applied to the case where both the true and the assumed shape of the investment outflow/benefit inflow relationships have benefit inflows that change exponentially over time. It is shown that if the exponential rate of change is mis-specified the resulting CRR-based estimate of the IRR will contain systematic bias monotonically related to the rate of growth.     

Futures and forward price differential and the effect of marking‐to‐market: Australian evidence

The objective of this paper is to examine the effects of marking‐to‐market of futures contracts on the price differential between futures and forward contracts based on the predictions of the Cox, Ingersoll and Ross (1981) (CIR) model. Cox et al ., (1981) derive a series of propositions with respect to the relationship between futures and forward prices and a set of testable implications. These are tested empirically in this paper using Australian data from November 1991 to June 1997. The results provide evidence of the presence of significant futures and forward price differences, where the futures price is consistently below the forward price. Only partial support is found for the Cox et al ., (1981) propositions, implying that the effect of marking‐to‐market is not able to fully account for the price differential. Therefore, it is not possible to rule out the influence of other institutional factors on the futures‐forward price difference.