Continuous Separation of an H2SO4/CuSO4 Mixture by Diffusion Dialysis

The separation of a mixture of sulfuric acid and copper sulfate is experimentally investigated in a two‐compartment countercurrent dialyzer at steady state using an anion‐exchange membrane. The dialysis process is characterized by the recovery yield of acid, the rejection coefficient of salt, and the permeability coefficient of the membrane. The simultaneous transport of sulfuric acid and copper sulfate is quantified by four phenomenological coefficients, which are dependent on the acid and salt concentrations in the feed. They are determined by a procedure consisting of (i) the numerical integration of the basic differential equations describing the concentration profiles of both components on both sides of the membrane and (ii) the optimizing method.     

Preventing Interference to DTV Broadcasting in Every Market From Unlicensed or Uncontrolled Clusters of Broadband Devices on Unoccupied DTV Channels

The threat of interference to licensed DTV by clusters of unlicensed and uncontrolled broadband devices (BDs) transmitting simultaneously on unoccupied DTV channels remains. DTV channels in major U.S. cities could be victimized by interference from unlicensed or uncontrollable clusters. This paper shows how and why interference by clusters of broadband devices would be significantly higher than interference by individual broadband devices or by interference from clusters of single-tone devices. This paper also provides a real-world assessment of the maximum interference that consumer-grade receivers can accept from clusters of broadband devices operating on unoccupied DTV channels. To prevent interference to DTV and to maximize spectral efficiency individual base stations would have to be licensed as part of a network, and portable unlicensed devices would have to be equipped with dual DTV tuners with GPS chips.     

DTV coverage and service prediction, measurement and performanceindices

It is now clear that methods used to predict the replication of the NTSC service in the United States were idealized and, for the most part, not validated. The need to review the methods and procedures now in use is highlighted by the various field tests conducted in the U.S. and elsewhere. This paper outlines potential improvements in the modeling, methods and procedures now in use for prediction and measurement of the DTV service     

Limits on Fixed Broadband Devices for Interference-Free Operation in the DTV Spectrum

This paper examines the limits that must be imposed on single and multiple fixed cognitive broadband devices (BDs) transmitting simultaneously on multiple unused TV channels in order to avoid interference with the reception of licensed TV channels. Single and multiple fixed BDs are assumed to radiate 4W peak power relative to an isotropic source and transmit within 10 meters of the nearest digital television (DTV) set antenna. The power and separation limits are shown to depend on whether BDs are licensed, on whether mandated minimum front-end performance specifications for DTV sets are in place, and on the definition of an ldquounused channel.rdquo Short and long-term general conclusions are drawn regarding the maximum allowable directional power and regarding taboo channels for interference-free coexistence with DTV sets. It is shown that unlicensed BDs would result in the least efficient use of the available DTV spectrum because the ldquoworst caserdquo interference limits must be imposed in an unlicensed environment. The most efficient utilization of the DTV spectrum would be achieved if BDs were licensed and then allowed to migrate, together with DTV channels, into two blocks of contiguous channels, one for DTV and one for BDs.     

Planning factors for fixed and portable DTTV reception

The transition plan from the analog (NTSC) to digital terrestrial television (DTTV) in the USA was based on a simplified version of the Longley-Rice service prediction algorithm, and a link budget that mimicked the traditional planning factors for NTSC. It is now clear that the service prediction and the link budget both have serious shortfalls. This paper provides the formalism required for the development of realistic link budget and service grades for fixed and portable DTTV reception.     

Will terrestrial broadcasting survive the HDTV standard?

Key analyses and specifications that the author asserts should have been part of the precertification process for HDTV systems are outlined. As part of the current precertification process, estimates for the channel and equipment impairments and the associated power penalties in the C/N (carrier-to-noise) are not required, the range of BER (bit error rate) for a given EFH (error free hours) is not specified, and the expected spectral spreading into adjacent channels due to the nonlinear power amplifier is hardly mentioned. The problems with the ATTC laboratory tests and field tests are discussed     

Television receiver optimization in the presence of adjacent channel interference

Improved DTTV reception in a crowded spectrum can be attained by automatically shifting the front-end filter and by automatically steering the pattern of the receive antenna. This paper shows how 3rd order intermodulation distortion (IM/sub 3/) and other interference due to strong adjacent channels can be minimized and the signal to noise ratio maximized for optimally robust reception.     

Immunoscintigraphy in the diagnosis of ovarian carcinoma

Spasticity after a stroke interferes with the normal function of a limb. Electric stimulation has been used in a variety of ways to decrease spasticity. The purposes of this study were (1) to quantify the effectiveness of electric stimulation on decreasing ankle spasticity and (2) to develop a quantitative assessment of muscle tone, which could be replicated in the clinic. Ten patients with hemiparesis resulting from ischemic stroke participated in the study according to the selection criteria. Their mean age was 57 yr, with a mean stroke interval of 12.5 months. Patients received electric stimulation for 45 min through surface electrodes applied to the skin in the 12th thoracic and 1st lumbar areas. All patients received five electric stimulation treatment sessions. The electrical pulses were amplitude modulated frequency beat with a carry frequency of 2500 Hz and a stimulation frequency of 20 Hz. The stimulation intensity was adjusted to each patient to produce a sensory stimulation. The pre- and posttreatment evaluation included surface electromyography activity during passive ankle dorsiflexion, passive ankle dorsiflexion resistance at different angular velocities, as measured by an isokinetic machine and the modified Ashworth scale. Our results indicate that the surface spinal cord stimulation with middle frequency modulated to low frequency for sensory stimulation on the skin of 12th thoracic and first lumbar area is effective in reducing calf muscle spasticity of hemiplegic patients. The isokinetic torque measures for spasticity are a sensitive tool to document the effects of the treatment.     

Interference to UHF-DTTV Channels by Unlicensed Devices

With the transition to digital terrestrial television (DTV) in the U.S. scheduled to be complete by 2009, the Federal Communications Commission (FCC) has issued a notice of proposed rule making (NPRM) that, if adopted, would allow transmission by unlicensed devices on frequencies of vacated television channels. The FCC is required by statute to avoid harmful interference to licensed TV channels. This paper addresses two of the core questions related to the proposed introduction of unlicensed transmissions in the vacated TV channels: Do the proposed rules provide DTV stations adequate protection from interference from these devices? If not, what rules must be adopted to avoid harmful interference to terrestrial DTV service from these devices?