30-40-GHz drain-pumped passive-mixer MMIC fabricated on VLSI SOI CMOS technology

In this paper, a passive down mixer is proposed, which is well suited for short-channel field-effect transistor technologies. The authors believe that this is the first drain-pumped transconductance mixer that requires no dc supply power. The monolithic microwave integrated circuit (MMIC) is fabricated using digital 90-nm silicon-on-insulator CMOS technology. All impedance matching, bias, and filter elements are implemented on the chip, which has a compact size of 0.5 mm/spl times/0.47 mm. The circuit covers a radio frequency range from 30 to 40 GHz. At a RF frequency of 35 GHz, an intermediate frequency of 2.5 GHz and a local-oscillator (LO) power of 7.5 dBm, a conversion loss of 4.6 dB, a single-sideband (SSB) noise figure (NF) of 7.9 dB, an 1-dB input compression point of -6 dBm, and a third-order intercept point at the input of 2 dBm were measured. At lower LO power of 0 dBm, a conversion loss of 6.3 dBm and an SSB NF of 9.7 dB were measured, making the mixer an excellent candidate for low power-consuming wireless local-area networks. All results include the pad parasitics. To the knowledge of the authors, this is the first CMOS mixer operating at millimeter-wave frequencies. The achieved conversion loss is even lower than for passive MMIC mixers using leading edge III/V technologies, showing the excellent suitability of digital CMOS technology for analog circuits at millimeter-wave frequencies.     

Performance of a high purity Ge gamma detection system cooled by a cryogenic refrigerator

The energy resolution and thermal performance of a high purity Ge-detector system cooled by a cryogenic refrigerator is described. The mechanical vibrations of the cryomachine are damped effectively leading to a degradation in energy resolution of 200 eV only. Cool-down time is two hours and output pulse height stability is excellent between 82 and 94 K. For data display and spectrum analysis an economic personal computer-based system is used.     

Cold Gas-Sprayed Deposition of Metallic Coatings onto Ceramic Substrates Using Laser Surface Texturing Pre-treatment

Cold spraying enables a variety of metals dense coatings onto metal surfaces. Supersonic gas jet accelerates particles which undergo with the substrate plastic deformation. Different bonding mechanisms can be created depending on the materials. The particle–substrate contact time, contact temperature and contact area upon impact are the parameters influencing physicochemical and mechanical bonds. The resultant bonding arose from plastic deformation of the particle and substrate and temperature increasing at the interface. The objective was to create specific topography to enable metallic particle adhesion onto ceramic substrates. Ceramic did not demonstrate deformation during the impact which minimized the intimate bonds. Laser surface texturing was hence used as prior surface treatment to create specific topography and to enable mechanical anchoring. Particle compressive states were necessary to build up coating. The coating deposition efficiency and adhesion strength were evaluated. Textured surface is required to obtain strong adhesion of metallic coatings onto ceramic substrates. Consequently, cold spray coating parameters depend on the target material and a methodology was established with particle parameters (diameters, velocities, temperatures) and particle/substrate properties to adapt the surface topography. Laser surface texturing is a promising tool to increase the cold spraying applications.     

Reducing the fuel use and greenhouse gas emissions of the US vehicle fleet

The unrelenting increase in the consumption of oil in the US light-duty vehicle fleet (cars and light trucks) presents an extremely challenging energy and environmental problem. A variety of propulsion technologies and fuels have the promise to reduce petroleum use and greenhouse gas emissions from motor vehicles. Even so, achieving a noticeable reduction on both fronts in the near term will require rapid penetration of these technologies into the vehicle fleet, and not all alternatives can meet both objectives simultaneously. Placing a much greater emphasis on reducing fuel consumption rather than improving vehicle performance can greatly reduce the required market penetration rates. Addressing the vehicle performance–size–fuel consumption trade-off should be the priority for policymakers rather than promoting specific vehicle technologies and fuels.     

Die Integration von Informationsverarbeitungsressourcen im Rahmen von Mergers & Acquisitions

Mergers & acquisitions feature prominently in today’s business world. At the same time, numerous failed transactions exemplify that the integration of enterprise resources requires special management attention. As corporate value chains become ever more permeated with information technology, integration in mergers & acquisitions increasingly turns into an issue of combining firms’ IT-resources. In face-to-face interviews with IT-managers, detailed insights into the integration of data centers, application suites and IT-organizations were gained for 20 horizontal, synergy-oriented mergers & acquisitions. A contingency model is used to analyze different integration practices for their situational drivers and success impact. The results offer support for business and IT-management in successfully integrating IT-resources in mergers & acquisitions.     

Quantification of aortic stenosis in mechanically ventilated patients using multiplane transesophageal Doppler echocardiography

OBJECTIVE: The development of sudden postoperative hearing loss as a complication of microvascular decompression (MVD) operations in the cerebellopontine angle has already been reported. A sudden hearing loss of vascular origin may also occur hours or days after such operations, but even in such cases an improvement of hearing over the following weeks is possible. Here we report on a gradual deterioration of hearing over a period of two weeks after MVD which has not been described in the literature up to now. CLINICAL PRESENTATION: A MVD operation was performed twice on a 36 year old patient with trigeminal neuralgia. After the second operation the patient developed a slight hearing impairment 3 days postoperatively which increased over a period of two weeks and ended up with total deafness. The course of intra-operative brainstem auditory evoked potentials and postoperative audiograms is documented. CONCLUSION: Because of gradual development of the delayed hearing loss, we conclude that postoperative tissue scarring may be the underlying pathology.     

Coating deposition and adhesion enhancements by laser surface texturing—metallic particles on different classes of substrates in cold spraying process

A nonsystematic study of metallic particle deposition behavior in kinetic spray process for three classes of substrate materials was performed (metallic, polymer, and ceramic). The particle–substrate contact time, temperature, and area upon impact were estimated for different topographies by numerical analysis. The results indicated that the deformation and the resultant bonding were dependent on the contact shape area. Laser surface texturing was used as a surface prior treatment to create specific topographies. The deposition efficiency and the adhesion strength were evaluated and compared with the numerical results. First, metal–metal couples investigated large adiabatic shear instability at the interface causing intimate adhesive bonds. It was maximized for cavities because the interface temperature and contact area were larger at the interface. Besides, the mechanical anchoring was more efficient with laser gripping zones. Then, metal deposition on polymer was a challenge. Particle embedded in the substrate only if the particle kinetic energy was sufficient to penetrate as far as its diameter. Cold spray process needed to be studied. However, concave shape indicated a larger deposition efficiency by minimizing bounces. Also, metallization of ceramic by cold spray demonstrated a problem due to a nondeformation of the substrate. So, particle compressive states were the key for mechanical anchoring, and it was provided by laser surface texturing. Finally, cold spray parameters and surface topography were dependant. A methodology was established with particle states and particle/substrate properties to adapt the surface topography to enhance deposition efficiency and adhesion. The window of deposition was larger for laser-treated surface. Laser surface texturing enabled an adapted surface structuration for many applications.     

Radiocarbon observations in atmospheric CO2: determining fossil fuel CO2 over Europe using Jungfraujoch observations as background

Monthly mean 14CO2 observations at two regional stations in Germany (Schauinsland observatory, Black Forest, and Heidelberg, upper Rhine valley) are compared with free tropospheric background measurements at the High Alpine Research Station Jungfraujoch (Swiss Alps) to estimate the regional fossil fuel CO2 surplus at the regional stations. The long-term mean fossil fuel CO2 surplus at Schauinsland is 1.31+/-0.09 ppm while it is 10.96+/-0.20 ppm in Heidelberg. No significant trend is observed at both sites over the last 20 years. Strong seasonal variations of the fossil fuel CO2 offsets indicate a strong seasonality of emissions but also of atmospheric dilution of ground level emissions by vertical mixing.