Impulse TDR and its application to measurement of antennas

The traditional stimulus signal used in a time-domain reflectometer (TDR) is a voltage step. We propose an alternative technique, whereby an impulse generator is employed in place of the step generator in a TDR. The advantage conferred by “impulse TDR” is that more energy is available at higher frequencies than with conventional step TDR, and so a higher bandwidth and signal-to-noise ratio (SNR) is achieved. The theoretical result is compared with measurement

Transfer as a reciprocal process: How to foster receptivity to results of transdisciplinary research

Transdisciplinary research (TDR) seeks to address real-world problems and aims to be socially transformative. This normative objective extends beyond particular TDR projects, as real-world problems are embedded in concrete contexts but, at the same time, are also related to wider societal challenges that are not restricted to one context. Therefore, TDR generally entails transfer of knowledge and results to other contexts. However, the TDR discourse has mainly treated transfer efforts from the perspective of scientific generalization, translation and packaging of knowledge. Within this understanding of transfer, little attention has been paid to interplay between contexts and the role of new contexts themselves. This article is based on qualitative explorative research on four TDR projects. Its results were iteratively derived through project analysis, reflection on insights from the literature and discussions with TDR experts. We propose that transfer is a complex reciprocal process in which different types of knowledge are provided and transferred to other contexts, where knowledge is adapted, enriched and modified. In addition to project researchers, actors in other (pick-up) contexts also play an important role for successful transfer and appropriation of TDR results. Generating transfer potential within the duration of a project depends on being aware of potential pick-up contexts. To address the interdependent aspects of transfer (results, mediation, and appropriation in other contexts), we present a comprehensive model outlining TDR transfer processes. To support projects seeking to raise their transfer potential in a more conscious manner, we also formulate three overarching recommendations: 1) process results for transfer adequately, 2) identify and support intermediaries and, 3) increase awareness of and address other contexts. Considering these recommendations while also being aware of their interdependence may increase potential for transfer of knowledge and results to other contexts. Our conceptual understanding acknowledges the complexity and non-linearity of endeavors to take advantage of case-specifically gained knowledge and results in other contexts or at other scales

Value relevance of troubled debt restructurings and policy implications

This paper investigates the beneficial economic consequences and market and accounting based valuation effects of troubled debt restructurings (TDR) in financially distressed debtor firms. Relying on the implications of prior research and extant valuation theories, some empirical evidence on the beneficial outcomes and informativeness of TDR is first provided: significantly positive restructuring interval excess returns and higher excess returns to subsequently consummated restructurings and subsequent survivors. The market reaction to “full-settlement” and “modification of terms” types of TDR are also measured to evaluate the consistency of the FASB's binary classification and recognition criteria with the market participants' assessments. Finally, a valuation model conditional on book values and earnings is used to test the value relevance of the reported financial statement bottom lines and TDR related disclosure. The findings suggest that modifications are at least as beneficial and informative as full settlements. Hence, the recognition of the reduction in the liability and the related gain in the financial statements of firms that undertake modifications would be more congruent with the valuation effects assessed by market participants. Key words: Private workouts, Financial distress, Debt restructuring, Valuation, Capital markets, SFAS No.15. JEL: G14, G33, G38, M4

Measurement of antennas and microwave components using time-domain reflectometry of a voltage impulse

Band-pass microwave systems such as ultra-wideband antennas are traditionally characterized in the frequency-domain through a vector network analyzer in an anechoic chamber. A recent study proved antennas could be accurately measured in the time-domain using a step-function time-domain reflectometer (TDR), without the need for an anechoic chamber. We propose a new advance in the TDR characterization method. An impulse generator is employed in place of the step generator in a TDR set-up. The advantage conferred by this change is that more energy is available beyond a given frequency than with a step, and so a higher signal-to-noise ratio is achieved. The theoretical result is compared with measurement

Can the Market Be Used to Preserve Land? The Case for Transfer of Development Rights

This paper discusses the use of a market-driven technique ? transfer of development rights ? to preserve land from development while guaranteeing the rights of property owners. While the technique is often used in the United States, Europe has a lot more urgency in land preservation but it is still lagging in the use of market based instruments such as transfer of development rights. Property ownership can be described as a bundle of rights, including the right to use, the right to exchange, and the right to convert. The transfer of development rights (TDR) technique assumes that the development rights of a parcel, as part of the right to convert, can be sold and used in another parcel. The motivation for the creation of a TDR program is the preservation of environmentally sensitive areas, agricultural land, open space, and historic landmarks. In the task of preserving these areas, TDR is thought to be the best technique since it is a market-type transaction involving low costs for the public, it is more effective than zoning in the protection of land and landmarks, and it provides compensation to landowners that alienate the development rights. The typical TDR program involves the landowner of a preservation or sending zone (or parcel) selling the development rights to a developer who will use these rights in an area designated as development or receiving zone (or parcel). In general, the receiving area allows higher density of construction, which becomes the incentive for developers to buy the development rights. A variation of this program occurs when government creates a TDR bank from which developers acquire rights to develop at higher densities and the government uses the money to purchase development rights in areas it wishes to protect. TDR banks can also help during economic recessions to sustain the price of certificates. The economic analysis argues that TDR programs should be preferred to zoning for four reasons. First, TDR programs are market-based alternatives and, therefore, entail less administrative costs then command-and-control regulation. Second, rezoning decisions frequently involve large rent-seeking costs, whereas TDR overcomes the market failure and increases the net benefits of regulation. Third, the certificates of development rights can be exchanged in the market and provide a compensation to the landowner for the loss of the right to develop. Fourth, in communities facing urban sprawl and suffering pressures to develop, the outcome of a TDR program is an efficient market allocation of land to its most valued use: the market maximizes the aggregate value of the land. The paper summarizes the economic arguments favoring the use of TDR programs and discusses the difficulties in implementing these programs in Europe where command-and-control regulation has been preferred over market-based solutions.

The Role of Probe Attenuation in the Time-Domain Reflectometry Characterization of Dielectrics

The influence of the measurement setup on the estimation of dielectric permittivity spectra from time-domain reflectometry (TDR) responses is investigated. The analysis is based on a simplified model of the TDR measurement setup, where an ideal voltage step is applied to an ideal transmission line that models the probe. The main result of this analysis is that the propagation in the probe has an inherent band limiting effect, and the estimation of the high-frequency permittivity parameters is well conditioned only if the wave attenuation for a round trip propagation in the dielectric sample is small. This is a general result, holding for most permittivity model and estimation scheme. It has been verified on real estimation problems by estimating the permittivity of liquid dielectrics and soil samples via an high-order model of the TDR setup and a parametric inversion approac

Synthetic TDR Measurements for TEM and GTEM Cell Characterization

This paper describes the main features of the timedomain reflectometry (TDR) measurement technique and, in particular, the TDR analysis performed using a proper operating mode of the vector network analyzer (VNA), which is called synthetic TDR. Furthermore, some results of reflection measurement, which aim to characterize the impedance behavior of transverse electromagnetic (TEM) and gigahertz TEM cells by means of a commercial VNA in time-domain mode, are presented

Prevalence of Transmitted HIV Drug Resistance Among Newly Diagnosed Antiretroviral Therapy-Naive Pregnant Women in Lilongwe and Blantyre, Malawi

In 2006, a survey of transmitted human immunodeficiency virus (HIV) drug resistance (TDR) was conducted in Lilongwe, Malawi. The survey followed the World Health Organization method to classify TDR to nucleoside reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs) among primigravid women aged <25 years. Results of the 2006 survey showed <5% TDR in all drug classes. In 2009, TDR surveys using the same method were repeated in Lilongwe and expanded to Blantyre. Findings show that in Lilongwe TDR to NRTIs and PIs was <5%, whereas TDR to NNRTIs was 5%-15%. In Blantyre, TDR was <5% to all drug classes. Observed moderate TDR in Lilongwe is cause for concern and signals the need for closer monitoring of Malawi's antiretroviral therapy progra

Tradable driving rights in urban areas: their potential for tackling congestion and traffic-related pollution

Congestion pricing as a transport demand management measure is difficult to implement because most of motorists expect a deterioration of their welfare. Tradable driving rights (TDR), that is allocating quotas of driving rights for free to urban inhabitants, could be a more acceptable alternative. This mechanism provides also a supplementary incentive to save whether trips or distance travelled by car, because of the possibility of selling unused rights. A complete system of TDR is designed in detail, aiming whether at reducing trips or vehicles-kilometres, in order to control congestion, or the same target modulated on the basis of the pollutant emission categories of vehicles in order to control atmospheric pollution. An assessment is carried out on the Lyon urban area, which points at some welfare distributive issues between motorists and the community, when compared with conventional congestion pricing.transport demand management (TMD) ; tradable driving rights (TDR) ; automobile traffic ; congestion pricing ; air pollution ; urban areas ; Lyon (France)