FPGA-based test bed for measurement of AM/AM and AM/PM distortion and modeling memory effects in RF PAs

Using a field-programmable gate array (FPGA) development board, a digital signal processor (DSP) builder, and the phase-to-amplitude conversion principle, a low-cost system for measuring the amplitude-to-amplitude (AM/AM) and amplitude-to-phase (AM/PM) distortion curves of radio frequency (RF) power amplifiers (PAs) is presented. The state of the art based on the measurements and preliminary studies of AM/AM and AM/PM distortion curves is discussed. A full digital control of the test bed simulated/emulated in Matlab/Simulink is introduced to recalculate the known AM/AM and AM/PM measurements stored as look-up table (LUT). Finally, the low-cost system comprises the memory polynomial model (MPM) that involves the nonlinearity order and memory effects of real PAs.     

干式变压器的抗震试验研究

本文中作者介绍了干式变压器的抗震试验原理,进行了抗震试验和试验结果分析,得出了试验结果,验证了样品刚度和强度性能。     

Maximum dry density test to quantify pumice content in natural soils

Crushable volcanic soils are well-known for their distinctive texture, vesicular nature and grain fragility. These features of volcanic soils lead to difficulty in interpreting the results of laboratory and field testing because of the occurrence of particle crushing. Sands containing pumice particles are commonly found in the Hamilton Basin in the North Island of New Zealand. The pumice particles originated from a series of volcanic eruptions centered in the Taupo and Rotorua regions. As a result of flooding and erosion along the Waikato River, the pumice particles have become mixed with other materials and have been distributed over the Hamilton Basin; these mixtures are referred to herein as natural pumiceous (NP) sands. This paper initially investigates an appropriate technique for measuring the maximum dry density (MDD) of NP sands; then a modified MDD test is proposed for estimating the pumice contents of these sands. In order to examine the applicability of different standard methods for determining MDD, New Zealand and Japanese standards are employed. The results using the Japanese standard show consistent MDD values when repeating the tests due to negligible particle crushing. On the other hand, the results of MDD tests according to the New Zealand standard indicate that a significant amount of particle crushing occurs after each repeated test and, consequently, it is not possible to get the same result when the test is repeated. NP sands reach their ultimate potential breakage during the modified MDD tests (at least, for the level of loading applied) and they experience different levels of particle crushing which may be a function of their pumice content. As a way forward, the relative breakages of the materials tested are used to estimate the pumice contents of the NP sands.     

Indirect test of M-S circuits using multiple specification band guarding

Testing analog and mixed-signal circuits is a costly task due to the required test time targets and high end technical resources. Indirect testing methods partially address these issues providing an efficient solution using easy to measure CUT information that correlates with circuit performances. In this work, a multiple specification band guarding technique is proposed as a method to achieve a test target of misclassified circuits. The acceptance/rejection test regions are encoded using octrees in the measurement space, where the band guarding factors precisely tune the test decision boundary according to the required test yield targets. The generated octree data structure serves to cluster the forthcoming circuits in the production testing phase by solely relying on indirect measurements. The combined use of octree based encoding and multiple specification band guarding makes the testing procedure fast, efficient and highly tunable. The proposed band guarding methodology has been applied to test a band-pass Butterworth filter under parametric variations. Promising simulation results are reported showing remarkable improvements when the multiple specification band guarding criterion is used.     

An algorithm for computing compatibly Frobenius split subvarieties

This paper describes an algorithm which produces all ideals compatible with a given surjective Frobenius near-splitting.     

Random Counts in Models and Structures (Volume 1)

Detailed examination of the lifetimes of components and assemblies by means of the usual sequential probability ratio tests is often not feasible because of the prohibitive time or cost involved in such an examination. Situations commonly arise, however, where extraneous information is available (perhaps in the form of experience of similar situations or concerning the reputation of the supplier of the components or assemblies) which reflects on the current situation. Such information might be incorporated in a Bayesian analysis, but little work seems to have been done in this area. This paper presents a possible sequential life test incorporating prior information, applied to the simplest situation of components with exponentially distributed lifetimes, tested individually. The results for conventional sequential lifetests are used as a rough yardstick against which to measure the properties of the Bayesian lifetest discussed in the paper.     

Peeking behind the screen: the unsuspected power of the standard Turing Test

No computer that had not experienced the world as we humans had could pass a rigorously administered standard Turing Test. This paper will show that the use of ‘subcognitive’ questions allows the standard Turing Test to indirectly probe the human subcognitive associative concept network built up over a lifetime of experience with the world. Not only can this probing reveal differences in cognitive abilities, but crucially, even differences in physical aspects of the candidates can be detected. Consequently, it is unnecessary to propose even harder versions of the Test in which all physical and behavioural aspects of the two candidates had to be indistinguishable before allowing the machine to pass the Test. Any machine that passed the ‘simpler’ symbols-in symbols-out test as originally proposed by Turing would be intelligent. The problem is that, even in its original form, the Turing Test is already too hard and too anthropocentric for any machine that was not a physical, social and behavioural carbon copy of ourselves to actually pass it. Consequently, the Turing Test, even in its standard version, is not a reasonable test for general machine intelligence. There is no need for an even stronger version of the Test.     

An adaptive ant colony optimization algorithm for constructing cognitive diagnosis tests

A critical issue in the applications of cognitive diagnosis models (CDMs) is how to construct a feasible test that achieves the optimal statistical performance for a given purpose. As it is hard to mathematically formulate the statistical performance of a CDM test based on the items used, exact algorithms are inapplicable to the problem. Existing test construction heuristics, however, suffer from either limited applicability or slow convergence. In order to efficiently approximate the optimal CDM test for different construction purposes, this paper proposes a novel test construction method based on ant colony optimization (ACO-TC). This method guides the test construction procedure with pheromone that represents previous construction experience and heuristic information that combines different item discrimination indices. Each test constructed is evaluated through simulation to ensure convergence towards the actual optimum. To further improve the search efficiency, an adaptation strategy is developed, which adjusts the design of heuristic information automatically according to the problem instance and the search stage. The effectiveness and efficiency of the proposed method is validated through a series of experiments with different conditions. Results show that compared with traditional test construction methods of CDMs, the proposed ACO-TC method can find a test with better statistical performance at a faster speed.     

Design and setup of a testing device to investigate a reduced sized attachment system mock up for the ITER EU HCPB-TBM under different mechanical loading conditions

In order to determine the forces acting on the EU-Helium Cooled Pebble Bed Test Blanket Module (HCPB-TBM) during operation, a measurement system is developed. Therefore, two force reconstruction (FR) methods using measured strain signals are selected that are suitable for the application to the TBM. The first one, the augmented Kalman filter is a combined deterministic-stochastic approach. A second FR method based on the concept of a model predictive controller is proposed in this paper, which uses an optimization algorithm. In order to test the selected methods a testing device has been built which can be used to apply different force excitations on a reduced sized TBM mock up and measure the resulting strain signals of 16 strain gages. A simple tube mock up has been designed and manufactured to test and calibrate the FR algorithms. In addition, a second TBM mock up with attachment system is described. Finally, first results of the FR of a worst-case test case from simulated strain data of the simple tube mock up are presented.