Tuning Time Research Articles

Study on Active Vibration Control for High-Speed Elevators

When elevators travel at high speed, horizontal vibrations of the car tend to occur due to guide rail deformations, deteriorating ride comfort. Therefore, several active control systems have been developed to reduce these vibrations. These systems consist of six actuators, which independently move the guide rollers. To reduce costs and installation time, it is necessary to develop a system with a minimum number of actuators and a simplified controller. We developed a system with only three actuators. The controller incorporates an H-infinity control design method for maintaining stability of the system when there is a change in load. Furthermore, from a practical point of view, it is important to reduce the order of the controller so that the time for on-site parameter tuning can be reduced. Therefore, we reduced the H-infinity controller to a P controller. We demonstrated that the maximum amplitude of vibrations of a car with active control system can be reduced to almost half the vibration amplitude without control.

Noncommutative double scalar fields in FRW cosmology as cosmical oscillators

We investigate the effects caused by noncommutativity of the phase space generated by two scalar fields that have non-minimal conformal couplings to the background curvature in the FRW cosmology. We restrict deformation of the minisuperspace to noncommutativity between the scalar fields and between their canonical conjugate momenta. Then, the investigation is carried out by means of a comparative analysis of the mathematical properties (supplemented with some diagrams) of the time evolution of variables in a classical model and the wavefunction of the universe in a quantum perspective, both in the commutative and noncommutative frames. We find that the imposition of noncommutativity causes more ability in tuning time solutions of the scalar fields and, hence, has important implications in the evolution of the Universe. We find that the noncommutative parameter in the momenta sector is the only responsible parameter for the noncommutative effects in the spatially flat universes. A distinguishing feature of the noncommutative solutions of the scalar fields is that they can be simulated with the well-known three harmonic oscillators depending on three values of the spatial curvature, namely the free, forced and damped harmonic oscillators corresponding to the flat, closed and open universes, respectively. In this respect, we call them cosmical oscillators. In particular, in closed universes, when the noncommutative parameters are small, the cosmical oscillators have an analogous effect with the familiar beating effect in the sound phenomena. Some of the special solutions in the classical model and the allowed wavefunctions in the quantum model make bounds on the values of the noncommutative parameters. The existence of a non-zero constant potential (i.e. a cosmological constant) does not change time evolutions of the scalar fields, but modifies the scale factor. An interesting feature of the well-behaved solutions of the wavefunctions is that the functional form of the radial part is the same as the commutative ones within a given replacement of constants caused by the noncommutative parameters. Furthermore, the Noether theorem has been employed to explore the effects of noncommutativity on the underlying symmetries in the commutative frame. Two of the six Noether symmetries of spatially flat universes, in general, are retained in the noncommutative case, and one out of the three in non-flat universes.

Bayesian experimental design of tracer studies to monitor wastewater leakage from sewer networks

Despite more than a decade of research, the magnitude of wastewater leakage from defective sewer systems into groundwater supplies is still largely unknown, partly because reliable measurement methods are lacking. Although recently suggested in‐sewer tracer studies present a promising solution, it is unclear how to optimally design such studies in network settings. In this study we present a formal experimental design procedure, which uses Bayesian data analysis to improve the diagnosis of sewer leakage by combining tracer test data with prior knowledge on network topology and condition. From a simulation study, we show that (1) if a single sewer section is expected to have high leakage, that section should be distinguished in measurement layouts through isolated tests or appropriate overlapping of multiple tests; (2) if multiple sections are expected to have high leakage, layouts with tests that cover more than one high‐leakage section should be avoided; and (3) if a robust experimental design is desired, a balanced layout of tests that overlap multiple sections of high leakage, yet minimizes stretch length, should be chosen. This design will have the additional benefit of inducing covariance in the posterior distribution of exfiltration estimates, which can be used to advantage in subsequent studies. We apply these guidelines to a case study of a catchment in Zurich, Switzerland, and find that optimal layout design can improve the anticipated gain of information substantially relative to designs based on practical considerations alone. Remaining concerns regarding the procedure include (1) the generally poor understanding of the mechanisms governing sewer leakage, which can hamper reliable prior information on exfiltration; (2) the currently low measurement precision of sewer tracer studies, which might only allow for the detection of large leaks; and (3) the need for numerical implementation of the Bayesian inference procedure, which requires careful tuning and long computation times. In general, we were able to demonstrate that the incorporation of prior information through a Bayesian procedure adds significant value to experimental design, especially in situations with few “hard” data but good site‐specific knowledge, which is common in water resources research.

Wavelength-Routed Networks With Lightpath Data Interchanges

We observe that tunable wavelength converters (TWCs) that are traditionally installed in wavelength-routed (WR) networks for wavelength contention resolution can be further utilized to provide fast data switching between lightpaths. This allows us to route a data unit through a sequence of lightpaths from source to destination if a direct single lightpath connection is not available or if we want to minimize the overhead of setting up new lightpaths. Since TWCs have a tuning time of picoseconds, it may be possible to use the installed TWCs as lightpath data interchanges (LPIs) to improve the performance of WR networks without significant optical hardware upgrade. Compared with the multihop electronic grooming approach of lightpath networks, the LPI approach has a simpler WR node architecture, does not need expensive high-speed electrical multiplexers/routers, and does not sacrifice the bit-rate/format transparency of data between the source and destination. Our simulation results show that WR networks with LPIs can have much lower blocking probability than WR networks without LPIs if the traffic duration is short. We show that LPIs can also be used to provide new data transportation services such as optical time division multiplexing access (OTDMA) time-slotted service in WR networks.

Low power and compact reconfigurable multiplexing devices based on silicon microring resonators

We present thermally reconfigurable multiplexing devices based on silicon microring resonators with low tuning power and low thermal crosstalk. Micro-heaters on top of the rings are employed to tune the resonant wavelengths through the thermo-optic effect of silicon. We achieve a low tuning power of 21 mW per free spectral range for a single ring by exploiting thermal isolation trenches close to the ring waveguides. Negligible thermal crosstalk is demonstrated for rings spaced by 15 microm, enabling compact multiplexing devices. The tuning time constant is demonstrated to be less than 10 micros.

Tunable Optical Dispersion Compensator Based on Power Splitting Between Two Dispersive Media

In this paper, we propose and experimentally demonstrate a novel tunable optical dispersion compensator (TODC). Dispersion compensation is achieved by splitting the input signal between two dispersive media and adding the resulting signals thereafter. Tunable compensation is attained by controlling the power splitting ratio of the input signal between both dispersive media. The frequency response of the TODC is theoretically assessed considering signal addition in the optical and electrical domains. The latter case is enabled by using optical single sideband (OSSB) modulation, which allows preserving the phase information of dispersive media output signals after direct detection. This is the only case experimentally tested, since it avoids stability problems related with coherent addition of optical signals. A TODC with a tuning range of -340 to 0 ps/nm was designed and experimentally assessed for a 40 Gb/s nonreturn-to-zero OSSB signal. The tunable power splitter consisted of an automatic polarization controller and a polarization beam splitter, which offered a tuning time lower than 150 ¿s. A bit error rate lower than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> was measured on the entire compensation range with a maximum power penalty of 3.3 dB relatively to an SSB signal in back-to-back.

Electrically ultra-fast tunable optical filter employing HiBi fiber and phase modulator

An electrically tunable optical filter with ultra-fast tuning time of a few picoseconds is proposed and demonstrated. The filter consists of a phase modulator with HiBi pigtails sandwiched between two polarizers. Tuning of 6.62 nm for a 16.06 nm FSR filter is obtained with an applied voltage of 0.9 V. Tuning speed at 10 Gb/s and risetime of 40 ps is demonstrated with a frequency shift keying modulation experimental setup. Faster tuning speed is potential since the scheme is based on the electro-optic effect of the LiNO 3 crystal with sub-picosecond response time.

Discussion on: “Simple Fractional Order Model Structures and their Applications in Control System Design”

Fractional calculus is about the integration or differentiation of non-integer orders. The use of “fractional” is purely due to historical reasons [1]. Using fractional order differential equations is believed to be able to better characterize the nature around us. Using an integer order model is only for our own convenience. Depending on the scale onwhich we characterize the dynamics of a system, more and more evidences are found that using fractional order model is ubiquitous and unavoidable [1, 2, 3]. For dynamic systems and controls, there are four possibilities 1) Integer-order plant model with integer order controller; 2) Integer-order plant model with fractional order controller; 3) Fractional-order plant with integerorder controller; and 4) Fractional-order plant model with fractional-order controller [2]. Case-1 is our traditional (integer-order) control. An example of Case 2) can be found in [3] and an example of Case-4 can be found in [4]. Examples for Case-3 are abundant such as conventional integer-order controls for flexible structures whose transfer functions are irrational or of fractional order. It is interesting to note that, reaction curve based rough modeling technique, although widely used in process industry to get a first order plus delay time (FOPDT) for initial tuning of a working PID controller with techniques such as Ziegler-Nichols tuning rule, has not been put enough emphasis in control textbooks.Webelieve that, every practicing control engineer and control engineering educator should pay attention to the importance of reaction

Variant methods of reduced set selection for reduced support vector machines

In dealing with large datasets the reduced support vector machine (RSVM) was proposed for the practical objective to overcome the computational difficulties as well as to reduce the model complexity. In this paper, we propose two new approaches to generate representative reduced set for RSVM. First, we introduce Clustering Reduced Support Vector Machine (CRSVM) that builds the model of RSVM via RBF (Gaussian kernel) construction. Applying clustering algorithm to each class, we can generate cluster centroids of each class and use them to form the reduced set which is used in RSVM. We also estimate the approximate density for each cluster to get the parameter used in Gaussian kernel which will save a lot of tuning time. Secondly, we present Systematic Sampling RSVM (SSRSVM) that incrementally selects the informative data points to form the reduced set while the RSVM used random selection scheme. SSRSVM starts with an extremely small initial reduced set and adds a portion of misclassified points into the reduced set iteratively based on the current classifier until the validation set correctness is large enough. We also show our methods, CRSVM and SSRSVM with smaller size of reduced set, have superior performance than the original random selection scheme.

Improvement of multi-hop packet transmission scheduling in WDM optical star networks

This paper addresses the design of multi-hop packet transmissions for the all-to-all broadcast ( AAB) problem in a wavelength division multiplexing (WDM) optical star network with N nodes. We assume that each node is equipped with a tunable transmitter and a fixed-tuned receiver (TT-FR), and each tunable transmitter needs a non-negligible tuning latency δ to switch between wavelengths. To reduce the number of O/E/O conversions in the multi-hop scheduling, the maximum hop distance of packet transmissions is limited to ρ . We propose an improved multi-hop scheduling algorithm to shorten the duration of scheduling periods. As ρ is odd, the number of tuning operations on each node is at most ⌈ 2 N / ( ρ + 1 ) ⌉ - 1 and the schedule length of our multi-hop scheduling is at most ( ⌈ 2 N ρ + 1 ⌉ - 1 ) ρ ( ρ + 1 ) 2 + δ . As ρ is even, the tuning time on each node is at most ⌈ 2 N / ρ ⌉ - 1 and the schedule length is at most ( ⌈ 2 N / ρ ⌉ - 1 ) ρ ( ρ - 1 ) 2 + δ . For general case, when ρ < 1 + δ + δ 2 - 6 δ + 5 2 , the schedule length of our multi-hop scheduling algorithm will be less than that of the optimal single-hop scheduling algorithm. This also improves the previous result on the multi-hop schedule length of the AAB problem.

Noncommutativity effects in FRW scalar field cosmology

We study effects of noncommutativity on the phase space generated by a non-minimal scalar field which is conformally coupled to the background curvature in an isotropic and homogeneous FRW cosmology. These effects are considered in two cases, when the potential of scalar field has zero and nonzero constant values. The investigation is carried out by means of a comparative detailed analysis of mathematical features of the evolution of universe and the most probable universe wave functions in classically commutative and noncommutative frames and quantum counterparts. The influence of noncommutativity is explored by the two noncommutative parameters of space and momentum sectors with a relative focus on the role of the noncommutative parameter of momentum sector. The solutions are presented with some of their numerical diagrams, in the commutative and noncommutative scenarios, and their properties are compared. We find that impose of noncommutativity in the momentum sector causes more ability in tuning time solutions of variables in classical level, and has more probable states of universe in quantum level. We also demonstrate that special solutions in classical and allowed wave functions in quantum models impose bounds on the values of noncommutative parameters.

Mechanistic cutting force model parameters evaluation in milling taking cutter radial runout into account

The simulation of the cutting process becomes a key aspect on production optimization. The search for optimal cutting parameters by simulation can be a very effective way of reducing the tuning time of the process and can demonstrate potential cost reduction. As the simulation of the microscopic behavior of the cut is still difficult to perform, most of the prediction techniques are based on mechanistic models of the cutting forces, whose parameters are deduced from experimental tests. The runout of the tool can be a parasite effect that lowers the precision of the identification of the cutting forces parameters. This paper shows the improvement of an identification algorithm given by the modeling of radial runout effect on the undeformed chip thickness. Two different models of cutter runout have been used and tested on experimental measurement performed on a static dynamometer. The adequacy between simulation and experiment is good and allows reliable prediction of cutting forces for different cutting conditions.

Pinwheel broadcast paradigm in supporting energy‐saving mobile devices

AbstractBecause of the limited bandwidth and restricted number of channels in the wireless access environment, the broadcast paradigm has become an important technique for accessing messages. Energy saving is an important issue in the mobile computing environment. In this paper, we propose a multichannel broadcast paradigm that constructs the broadcast channels according to the access frequency of each type of message in order to save energy in mobile devices (MDs). The pinwheel scheduling algorithm (PSA) presented in this paper is used to organize all types of messages in the broadcast channels in the most symmetrical distribution in order to reduce both the tuning time and the access time. The performance of the proposed mechanism is analyzed, and the improvement over existing methods is demonstrated numerically. The results show that the proposed mechanism is capable of improving both the tuning time and the access time due to the presence of skewness in the access distribution among the disseminated messages. When the number of message types increases, both the tuning time and the access time can be further improved as long as a small number of broadcast channels are added. Copyright © 2009 John Wiley &amp; Sons, Ltd.

XIR: Efficient Cache Invalidation Strategies for XML Data in Wireless Environments

With the growth of wireless computing and the popularity of eXtensible Markup Language (XML), wireless XML data management is emerging as an important research area. In this paper, cache invalidation methodology with XML update is addressed in wireless computing environments. A family of XML cache invalidation strategies, called S-XIR, D-XIR and E-XIR, is suggested. Using S-XIR and D-XIR, the unchanged part of XML data, only its structure changes, can be effectively reused in client caching. E-XIR, which uses prefetching, can further improve access time. Simulations are carried out to evaluate the proposed methodology; they show that the proposed strategies improve both tuning time and access time significantly. In particular, the proposed strategies are on average about 4 to 12 times better than the previous approach in terms of tuning time.

Tethyan–Mediterranean organic carbon‐rich sediments from Mesozoic black shales to sapropels

AbstractThe Jurassic to Holocene record of black shale deposition in the Tethys‐Mediterranean region is unrivalled by that of any other ocean basin, either in land sections or drill cores. The term ‘black shale’ is used here broadly for sediments with elevated organic carbon concentrations (&gt; 1%), including the Pliocene to Recent sapropels. Most of the black shales are devoid of benthonic organisms, are laminated, and were deposited in distinct rhythms during periods when the deep waters of the ocean basins were anoxic or dysoxic. The Tethyan black shale records have become essential in studies of the transfer of organic carbon into the sediment record and for astronomical tuning and geological time scales. These records have been central in understanding climate control on ocean dynamics and biogeochemical cycles. The Mesozoic black shales were deposited within well‐defined time envelopes of around 0·5 to 1 Myr. These black shales, which were confined to certain chronostratigraphic intervals in the Jurassic and Cretaceous, were recognized as expressions of global Oceanic Anoxic Events in the mid‐1970s and subsequently named after prominent researchers (Bonarelli, Selli, Goguel). The black shale episodes were dated by biostratigraphic methods and by high‐resolution chemostratigraphy and cyclostratigraphy. Mesozoic black shales are now interpreted as the oceanographic expression of major perturbations of the global carbon cycle and climate. Research into younger (Pliocene to Pleistocene) sedimentary cycles (including black shales, termed sapropels) exposed in land sections, or found in pelagic and hemipelagic marine sediment cores of Late Quaternary age, started in the 1950s. Main threads pursued from this end of the record were the climatic control of oceanic processes that permitted the development of highly detailed and precise time scales tuned to the astronomical clock of insolation changes, palaeoclimate evolution of the circum‐Mediterranean area and biogeochemical dynamics in anoxic basins. After 50 years of intensive research, the Tethyan and Mediterranean black shales remain subjects of fascination in Earth Science. Tracing the origins and building upon recent progress, the current hypotheses on their formation are reviewed here. It is a panorama of complex interplays between global and regional tectonics, climate dynamics during both Ice House and Greenhouse states of global and regional climate, oceanographic responses to these climate changes, and biogeochemical adaptations that were all needed to shape an extraordinary archive of global change in the absence of human activity.

A Cell-Based Hybrid Indexing Scheme for Energy Conserving k Nearest Neighbor Search on Air

This letter proposes a Cell-based Hybrid Index (CHI) for energy conserving k Nearest Neighbor search on air. The proposed CHI provides global knowledge on data distribution for fast decision of the search space and local knowledge for efficient pruning of data items. Simulations show that CHI outperforms the existing indexing schemes in terms of tuning time and energy efficiency. With respect to access time, it outperforms them except the distributed indexing scheme optimized for access time.

An Efficient Metropolitan WDM Ring Architecture for a Slotted Transmission Technique

In this paper, we present a wavelength division multiplexing multiring metropolitan area network architecture using a separate ring as control channel and a finite number of access nodes. Each access node is equipped with a fixed tuned transmitter and a fixed tuned receiver to exchange control information over the control wavelength. Also, each access node has a tunable transmitter to efficiently exploit all data wavelengths for data transmission. The set of data wavelengths is divided into wavelength bands. This allows a flexible node design with a number of parallel tunable receivers per node, each operating in a specific wavelength band and providing limited tuning time. On the one hand, our network strategy confronts more efficiently the scalability and maintenance problems comparatively with most of the access ring protocols. On the other hand, the proposed access algorithm avoids both the data wavelengths and the receiver collisions, improving even more the network utilization. An analytic model is developed for the performance measures evaluation. Also, we develop another analysis approach using discrete event simulation model based on self-similar statistics. Analysis is accomplished studying various numbers of access nodes, data wavelengths, and buffer size.

Analyze the Performance of the Cyclic Indexing Schemes for the Wireless Data Broadcast

Wireless data broadcast is an effective approach to disseminate information to a massive number of users. Indexing techniques for broadcasting data can reduce the battery power consumptions of mobile terminals by decreasing the tuning time. The organization of the indexes affects the efficiency of data searching. We investigate how the degree of the index node affects the tuning time, and thus minimize the power consumption of user's terminals. We proposed a performance measurement for the tuning time and a cyclic indexing algorithm. The numerical results suggest the degree of an index node be 3 when the access probabilities of the data tend to be uniformly distributed so that the expected tuning time is minimal. When the access distribution of the data nodes is skewer, the tuning time can be minimized by setting the degree in the index node 2.

Tunable VCSEL with ultra-thin high contrast grating for high-speed tuning

We report a nano-electromechanical optoelectronic (NEMO) tunable vertical-cavity surface-emitting laser (VCSEL) with an ultra-thin (145 nm) electrostatically actuated high-index-contrast subwavelength grating (HCG) designed to strongly reflect TE-polarized light. Single mode emission (SMSR >45 dB) and continuous wavelength tuning (approximately 4 nm) were obtained at room temperature with output power up to 2 mW under continuous wave (CW) operation. A record short wavelength tuning time (approximately 90 ns) is experimentally demonstrated, which is >100 times faster than previously reported DBR-based tunable VCSELs and a 1.7 times improvement over the previously reported TM polarized NEMO tunable VCSELs.

PEAK—a fast and effective performance tuning system via compiler optimization orchestration

Compile-time optimizations generally improve program performance. Nevertheless, degradations caused by individual compiler optimization techniques are to be expected. Feedback-directed optimization orchestration systems generate optimized code versions under a series of optimization combinations, evaluate their performance, and search for the best version. One challenge to such systems is to tune program performance quickly in an exponential search space. Another challenge is to achieve high program performance, considering that optimizations interact. Aiming at these two goals, this article presents an automated performance tuning system, PEAK , which searches for the best compiler optimization combinations for the important code sections in a program. The major contributions made in this work are as follows: (1) An algorithm called Combined Elimination (CE) is developed to explore the optimization space quickly and effectively; (2) Three fast and accurate rating methods are designed to evaluate the performance of an optimized code section based on a partial execution of the program; (3) An algorithm is developed to identify important code sections as candidates for performance tuning by trading off tuning speed and tuned program performance; and (4) A set of compiler tools are implemented to automate optimization orchestration. Orchestrating optimization options in SUN Forte compilers at the whole-program level, our CE algorithm improves performance by 10.8% over the SPEC CPU2000 FP baseline setting, compared to 5.6% improved by manual tuning. Orchestrating GCC O3 optimizations, CE improves performance by 12% over O3, the highest optimization level. Applying the rating methods, PEAK reduces tuning time from 2.19 hours to 5.85 minutes on average, while achieving equal or better program performance.