Module failure isolation circuit for paralleled inverters

A module failure isolation circuit is described which senses and averages the collector current of each paralled inverter power transistor and compares the collector current of each power transistor the average collector current of all power transistors to determine when the sensed collector current of a power transistor in any one inverter falls below a predetermined ratio of the average collector current. The module associated with any transistor that fails to maintain a current level above the predetermined radio of the average collector current is then shut off. A separate circuit detects when there is no load, or a light load, to inhibit operation of the isolation circuit during no load or light load conditions

Methods to improve recruitment to randomised controlled trials : Cochrane systematic review and meta-analysis

Peer reviewedPublisher PD

Reconfiguring redundancy management

A redundancy management system is described wherein input signals from a sensor are provided redundantly in parallel so that a primary control signal may be selected. Median value signals for groups of three sensors are detected in median value selectors of selection filter. The detected median value signals are then also compared in a subtractor/comparator to determine whether any of them exceed the others by an amount greater than the signal level for a failed sensor. If so, the exceeding detected medium value signal is sent to a control computer as the primary control signal. If not, the lowest level detected medium value signal is sent as the primary control signal

Lightning current waveform measuring system

An apparatus is described for monitoring current waveforms produced by lightning strikes which generate currents in an elongated cable. These currents are converted to voltages and to light waves for being transmitted over an optical cable to a remote location. At the remote location, the waves are reconstructed back into electrical waves for being stored into a memory. The information is stored within the memory with a timing signal so that only different signals need be stored in order to reconstruct the wave form

Phase detector for three-phase power factor controller

A phase detector for the three phase power factor controller (PFC) is described. The phase detector for each phase includes an operational amplifier which senses the current phase angle for that phase by sensing the voltage across the phase thyristor. Common mode rejection is achieved by providing positive feedback between the input and output of the voltage sensing operational amplifier. this feedback preferably comprises a resistor connected between the output and input of the operational amplifier. The novelty of the invention resides in providing positive feedback such that switching of the operational amplifier is synchronized with switching of the voltage across the thyristor. The invention provides a solution to problems associated with high common mode voltage and enables use of lower cost components than would be required by other approaches

Digital data reformatter/deserializer

A method and apparatus is presented for reformatting and de-serializing a serially-received sequence of data words, each consisting of a fixed number of binary data bits. A block of nm bits is serially fed into a shift register or serially-connected group of shift registers. In lieu of the(nm-1)th shifts, the bits are rearranged within the shift register in parallel fashion, according to a prescribed scheme. Shifting then continues, until the first bit of each data word appears in the last bit position in the shift register, at which time that data word is shifted in parallel into an output buffer stage, from which it is outputted in parallel, after a fixed delay

Total or near-total thyroidectomy versus subtotal thyroidectomy for multinodular non-toxic goitre in adults

Background Total thyroidectomy (TT) and subtotal thyroidectomy (ST) are worldwide treatment options for multinodular non-toxic goitre in adults. Near TT, defined as a postoperative thyroid remnant less than 1 mL, is supposed to be a similarly effective but safer option than TT. ST has been shown to be marginally safer than TT, but it may leave an undetected thyroid cancer in place. Objectives The objective was to assess the effects of total or near-total thyroidectomy compared to subtotal thyroidectomy for multinodular non-toxic goitre. Search methods We searched the Cochrane Library, MEDLINE, PubMed, EMBASE, as well as the ICTRP Search Portal and ClinicalTrials.gov. The date of the last search was 18 June 2015 for all databases. No language restrictions were applied. Selection criteria Two review authors independently scanned the abstract, title or both sections of every record retrieved to identify randomised controlled trials (RCTs) on thyroidectomy for multinodular non-toxic goitre for further assessment. Data collection and analysis Two review authors independently extracted data, assessed studies for risk of bias and evaluated overall study quality utilising the GRADE instrument. We calculated the odds ratio (OR) and corresponding 95% confidence interval (CI) for dichotomous outcomes. A random-effects model was used for pooling data. Main results We examined 1430 records, scrutinized 14 full-text publications and included four RCTs. Altogether 1305 participants entered the four trials, 543 participants were randomised to TT and 762 participants to ST. A total of 98% and 97% of participants finished the trials in the TT and ST groups, respectively. Two trials had a duration of follow-up between 12 and 39 months and two trials a follow-up of 5 and 10 years, respectively. Risk of bias across studies was mainly unknown for selection, performance and detection bias. Attrition bias was generally low and reporting bias high for some outcomes. In the short-term postoperative period no deaths were reported for both TT and ST groups. However, longer-term data on all-cause mortality were not reported (1284 participants; 4 trials; moderate quality evidence). Goiter recurrence was lower in the TT group compared to ST. Goiters recurred in 0.2% (1/425) of the TT group compared to 8.4% (53/632) of the ST group (OR 0.05 (95% CI 0.01 to 0.21); P < 0.0001; 1057 participants; 3 trials; moderate quality evidence). Re-intervention due to goitre recurrence was lower in the TT group compared to ST. Re-intervention was necessary in 0.5% (1/191) of TT patients compared to 0.8% (3/379)of ST patients (OR 0.66 (95% CI 0.07 to 6.38); P = 0.72; 570 participants; 1 trial; low quality evidence). The incidence of permanent recurrent laryngeal nerve palsy was lower for ST compared with TT. Permanent recurrent laryngeal nerve palsy occurred in 0.8% (6/741) of ST patients compared to 0.7% (4/543) of TT patients (OR 1.28, (95% CI 0.38 to 4.36); P = 0.69; 1275 participants; 4 trials; low quality evidence). The incidence of permanent hypoparathyroidism was lower for ST compared with TT. Permanent hypoparathyroidism occurred in 0.1% (1/741) of ST patients compared to 0.6% (3/543) of TT patients (OR 3.09 (95% CI 0.45 to 21.36); P = 0.25; 1275 participants: 4 trials; low quality evidence). The incidence of thyroid cancer was lower for ST compared with TT. Thyroid cancer occurred in 6.1% (41/669) of ST patients compared to 7.3% (34/465)of TT patients (OR 1.32 (95% CI 0.81 to 2.15); P = 0.27; 1134 participants; 3 trials; low quality evidence). No data on health-related quality of life or socioeconomic effects were reported in the included studies. Authors' conclusions The body of evidence on TT compared with ST is limited. Goiter recurrence is reduced following TT. The effects on other key outcomes such as re-interventions due to goitre recurrence, adverse events and thyroid cancer incidence are uncertain. New long-term RCTs with additional data such as surgeons level of experience, treatment volume of surgical centres and details on techniques used are needed

Apparatus for measuring a sorbate dispersed in a fluid stream

A sensitive, miniature apparatus was designed for measuring low concentrations of a sorbate dispersed in a fluid stream. The device consists of an elongated body having a surface capable of sorbing an amount of the sorbate proportional to the concentration in the fluid stream and propagating acoustic energy along its length. The acoustic energy is converted to an electrical output signal corresponding to the concentration of sorbate in the fluid stream. The device can be designed to exhibit high sensitivity to extremely small amounts of sorbate dispersed in a fluid stream and to exhibit low sensitivity to large amounts of sorbate. Another advantage is that the apparatus may be formed in a microminiature size and at a low cost using bath microfabrication technology

Spiral slotted phased antenna array

A flush mounting, cavity-backed, dual orthogonal slot antenna for aircraft and space vehicles is described. Improved radiation pattern characteristics are obtained by making the spiral slot pattern elliptical in the aperture plane. A cavity and a flanged aperture plate are configured such that one slot pair is orthogonal with respect to another slot pair within the aperture plate. Coaxial split-tube baluns are used to drive the junctions between corresponding slot pairs. An optional cavity dielectric is provided and a drive coupling arrangement includes a four port comparator hybrid having sum and difference ports respectively, for alternate excitation to produce a single lobe or a double lobe pattern with null. Switching apparatus is provided to connect a common terminal to either of the ports