Bar State Research Articles

Polymer Optical Waveguide Switch Using Thermo-Optic Total-Internal-Reflection and Strain-Effect

A new optical waveguide switch using thermo-optic total-internal-reflection and strain-induced effects in polymer materials has been experimentally demonstrated. The switch consists of three-layered slab waveguides and two metal strip lines that are located close to one another on top of the upper cladding. The deposition of metal strips introduces strain in the underlying polymer materials, creating two strain-induced optical waveguides for the cross state. Current applied along these metal strips results in a thermo-optic based total-internal-reflection waveguide between the two metal strips for the bar state. The fabrication and the device characteristics of the new optical switch are reported.

A NEW STRUCTURE OF MMI POLYMER THERMO-OPTIC SWITCH WITH A HIGH REFRACTIVE INDEX CONTRAST

The 2 £ 2 MMI polymer thermo-optic switch in a high refractive index contrast (0.102) with a new structure design is realized. This device was fabricated using standard fabrication techniques such as coating, photolithography, and dry etching. A crosstalk level of i36:2dB has been achieved. Meanwhile the extinction ratio of 36.1dB has been achieved in this device. The polarization dependent loss (PDL) of 0.3dB and Insertion loss of 1.4dB were measured at 1550nm wavelength. In terms of wavelength dependency, the device shows a good performance within C-band wavelength with vacillation of the insertion loss value around 0.88dB. The power consumption of 1.85mW was measured to change the state of the switch from the cross to bar state. The measured switching time was 0.7ms.

Support vector machine for fault diagnosis of the broken rotor bars of squirrel-cage induction motor

The paper presents an automatic computerized system for the diagnosis of the rotor bars of the induction electrical motor by applying the support vector machine. Two solutions of diagnostic system have been elaborated. The first one, called fault detection, discovers only the case of the fault occurrence. The second one (complex diagnosis) is able to find which bars have been damaged. The most important problem is concerned with the generation and selection of the diagnostic features, on the basis of which the recognition of the state of the rotor bars is done. In our approach, we use the spectral information of the motor current, voltage and shaft field of one phase registered in an instantaneous form. The selected features form the input vector applied to the support vector machine, used as the classifier. The results of the numerical experiments are presented and discussed in the paper.

High-Speed 2$\, \times \,$2 Switch for Multiwavelength Silicon-Photonic Networks–On-Chip

We report the fabrication and experimental verification of a multiwavelength high-speed 2 times 2 silicon photonic switch for ultrahigh-bandwidth message routing in optical on-chip networks. The structure employs only two microring resonators in order to implement the bar and cross states of the switch. These states are toggled using an optical pump at 1.5-mum wavelengths inplane with the waveguide devices, though electronic, rather than optical, control schemes are envisioned for more complex systems built from these devices. Experiments characterize bit-error-rate performance in the bar and cross states during static and dynamic operation. The all-optical demonstration exhibits the ability of the switch to implement ultra-short transition times (<2 ns), high extinction ratios (>10 dB), and low power penalties (~1 dB) at a data rate of 10 Gb/s. Further performance improvements are expected by using electronic carrier injection via p-i-n diodes surrounding the ring waveguides. The 2 times 2 switching functionality facilitates the design of more complex routing structures, allowing the implementation of high-functionality integrated optical networks.

All-optical nonlinear switching cell made of photonic crystal

We analyze and propose a directional optical coupler embedded in photonic crystal, which is driven by an external command signal. Therefore, this switching cell can work in an all-optical switch. The switching method uses a low-power external command signal, inserted in the central coupling region, which acts as another waveguide. The switching process is based on the change from the bar state to the cross state due to the external command signal. In our simulations we used the plane wave expansion method, finite-difference time-domain method, and our own binary propagation method.

Switching cell of directional coupler embedded in photonic crystal driven by an external command (for the C, L, and U bands of ITU)

We analyze and propose a directional optical coupler embedded in photonic crystal (PhC), which is driven by an external command signal. The switching method uses a low power external command signal, inserted in the central coupling region, which acts as another waveguide. The switching process is based on the change of the coupler from the bar state to the cross state owing to the external command signal.

Morphodynamic response of a meso- to macro-tidal intermediate beach based on a long-term data set

Four years of bi-monthly topographic surveys have been conducted on a 350 m stretch of the meso- to macro-tidal Truc Vert beach, France. Here we study the dynamics of both the inner bar and the upper part of the beach where a berm can develop in the presence of fair weather conditions. For the inner bar, the occurrences of the different states within the intermediate classification, following that of Wright and Short (Wright, L.D., Short, A.D. 1984. Morphodynamic variability of surf zones and beaches: a synthesis. Marine Geology 56, 93–118), are presented and compared to other sites in both micro- and meso-tidal environments. The results show a similar frequency of occurrence of the Transverse Bar and Rip (TBR) state, while the more dissipative states, Rhythmic Bar and Beach (RBB) and Longshore Bar and Trough (LBT), are less regularly observed despite the high wave energy levels. The LBT and RBB states are also observed in the presence of fair weather conditions and the TBR state can persist during very energetic events. Similar results are also observed with the upper beach dynamics. Very energetic events are not necessarily associated with erosion while and low-energy events are not necessarily accompanied by accretion. The conditions given here indicate, that berm development occurs preferentially when the beach morphology exhibits a TBR or a LTT state. Apart from the control exerted by offshore wave conditions, the beach state and berm development patterns exhibited by Truc Vert beach are also discussed within the framework of possible morphological (morphodynamic) feedback and of the influence of the meso- to macrotidal range which modulates the type, intensity and duration of the wave processes operating on the cross-shore profile.

Proposal of a small self-holding 2*2 optical switch using phase-change material

A small and fast self-holding 2 × 2 optical switch using phase change material is proposed. This switch is based on a directional coupler in which a short waveguide made of a phase-change material (PCM) is sandwiched between two Si waveguides. The characteristics of the proposed switch were simulated by a beam propagation method (BPM). This switch can be as small as 3µm × 21µm because the change in the refractive index of PCMs between the crystalline and amorphous states is very large; in addition, by utilizing the self-holding characteristics, it has the potential for low power consumption. The loss and the crosstalk were calculated to be 2.5dB and -20.4dB in the bar state and 1.3dB and -14.3dB in the cross state, respectively.

Experimental research on an integrated thermooptic switch based on multimode interference couplers

The experimental results of a 2 × 2 integrated thermooptic Mach-Zehnder interferometer (MZI) switch based on multimode interference (MMI) couplers are reported. The insertion loss (IL) is 3.40 dB, the polarization dependent loss is 0.47 dB, the extinction ratio (ER) at bar state and cross state is 32.01 dB and 16.42 dB respectively, the response time is less than 3 ms, and the power consumption is 658 mW. Regarding the asymmetry of extinction ratio at bar state and cross state, theoretical analysis is first presented. The coupling ratio of the two MMI couplers deviates from 50:50 but the deviation is nearly the same, which is decided by good uniformity of semiconductor planar lightwave circuit (PLC) process. This property affects the extinction ratio at bar state and cross state in different mechanisms. Adding a metal electrode on the waveguide affects its effective index and analysis based on experimental results is given. The increment of waveguide effective index is in the order of 2 × 10−4.

Design and Evaluation of a Haptic Flight Director

The majority of information sources on the flight deck are vis ual displays. An example is the flight director display that improves pilot ma nual aircraft control performance but also involves a visually demanding task. Tactile, or haptic displays use the human tactile modality as an information channel. This paper discusses how the visual information of the flight director can be presented th rough providing forcefeedback on the control stick. The haptic flight director giv es pilots a constant stream of tactile information on the state of the flight director com mand bars, even when visual attention is not directed at the primary flight displa y. It was hypothesized that the shorter latencies in the tactile motor loop allow pilots to control aircraft at a higher bandwidth, increasing performance. It was further hypothesized that using two modalities, instead of one, to conduct the aircraft manual control task, would reduce pilot workload, also when a secondary, visually distracting side task is present. To test these hypotheses an experiment was conducted in a fixe d-base simulator. Professional pilots conducted approaches with the visual and haptic flight director displays, while simultaneously a secondary task had to be conducted. Results show that the haptic flight director indeed yields improved pilot perf ormance and lower workload in tasks where pilots’ visual attention is distracted.

An Exploratory Study of How Developers Seek, Relate, and Collect Relevant Information during Software Maintenance Tasks

Much of software developers' time is spent understanding unfamiliar code. To better understand how developers gain this understanding and how software development environments might be involved, a study was performed in which developers were given an unfamiliar program and asked to work on two debugging tasks and three enhancement tasks for 70 minutes. The study found that developers interleaved three activities. They began by searching for relevant code both manually and using search tools; however, they based their searches on limited and misrepresentative cues in the code, environment, and executing program, often leading to failed searches. When developers found relevant code, they followed its incoming and outgoing dependencies, often returning to it and navigating its other dependencies; while doing so, however, Eclipse's navigational tools caused significant overhead. Developers collected code and other information that they believed would be necessary to edit, duplicate, or otherwise refer to later by encoding it in the interactive state of Eclipse's package explorer, file tabs, and scroll bars. However, developers lost track of relevant code as these interfaces were used for other tasks, and developers were forced to find it again. These issues caused developers to spend, on average, 35 percent of their time performing the mechanics of navigation within and between source files. These observations suggest a new model of program understanding grounded in theories of information foraging and suggest ideas for tools that help developers seek, relate, and collect information in a more effective and explicit manner.

Design and fabrication of a broadband polymer vertically coupled optical switch

This paper presents a detailed design and fabrication of a composite broadband polymer vertically coupled optical switch with a spectral extinction ratio variation less than 1 dB for the cross state and 2.5 dB for the bar state. This switch consists of two pairs of basic three-dimensional (3-D) polymer switches with peak coupling wavelengths located at the two ends of the C-band, respectively. The resultant extinction ratio is shown to be the sum of the individual ratios of the two basic switches that the optical signal propagates through. The rise time and fall time of switching are 1.0 and 1.5 ms, respectively, and the total electric power applied to the electrode heater is about 140 mW.

Crosstalk-minimized polymeric 2/spl times/2 thermooptic switch

A thermooptic 2/spl times/2 switch based on the total internal reflection effect is demonstrated. The device, made of ultraviolet curable fluorinated polymer, has an increased half-branch angle of 5/spl deg/. The purpose of a large half-branch angle is to overcome the volume relaxation phenomenon, which is an intrinsic characteristic of polymers. The device successfully decreases the crosstalk below -40 dB in both the cross and bar states. The fabricated device has a power consumption of only 66 mW in the bar state.

Optical switch based on multimode interference coupler

An optical switch based on the multimode interference (MMI) coupler is demonstrated in this letter. The device is designed and fabricated in polymeric materials and the thermooptic (TO) effect of polymers, which has a negative TO coefficient, is employed to change the self-imaging effect of a side-heated MMI coupler and realize optical switching. The switching power is only 22 mW. The experimental results show that the crosstalk of the switch is about -20 dB at both the cross and bar states.

Color nonsinglet spectroscopy

Study of the spectrum and structure of color non-singlet combinations of quarks and antiquarks, neutralized by a non-dynamical compensating color source, may provide an interesting way to address questions about QCD that cannot be addressed by experiment at the present time. These states can be simulated in lattice QCD and the results can be used to improve phenomenological models of hadrons. Here these ideas are applied to color triplet states of qqqq and qq bar q.

Aggression and fighting ability are correlated in the swordtail fish Xiphophorus cortezi: the advantage of being barless

Males of the swordtail fish Xiphophorus cortezi are polymorphic for the pigment pattern vertical bars. Previous studies indicate that barred males exhibit higher levels of aggression towards males with bars than those without, while barless males fail to exhibit differential levels of aggression to either morph. In this study I matched barred and barless males for size and paired them in dyadic contests in order to determine if either morph was more dominant and if so, if dominance was the result of higher aggression levels. I found that barless males had higher bite frequencies and were able to win a majority of the contests while barred males consistently escalated to biting first, even though in most cases they were ultimately the losers. In order to determine whether the observed aggression levels and fighting abilities were inherent to being barless or a consequence of responses to the bars themselves, the dyads were re-paired once after barless males were given temporary bars and once after barred males had their bars removed. Thus, each morph encountered his opponent in both a barred and barless state. Regardless of bar state, naturally barless males continued to be more aggressive and more dominant than their barred counterparts. In addition, naturally barred males only won contests in which they bit more. These results indicate that for this species, aggression is an important component of winning contests when opponents are roughly the same size. As a result, naturally barless males as a whole appear to have higher resource holding potential (RHP) than naturally barred males of the same size because of their greater aggression levels.

편광에 관계없이 매우 높은 소멸비와 짧은 길이를 가지는 수직 방향성 결합기 스위치

We propose a novel vertical directional coupler switch using a vertical directional coupler with polarization independent coupling lengths employing the doublesided deep-ridge waveguide structure. This switch is composed of a switching operation induced section with symmetric structures and an extinction ratio enhanced section with asymmetric structures. We present design methods and examples for this switch with very short lengths and very high extinction ratios larger than 30 dB for both TE and TM modes in cases of both cross and bar states.

Application of an integrated power line signal analysis methodology to the detection of major rotating machine abnormalities in nuclear power plants

An integrated and improved method to detect and identify the abnormality of motor driven rotating machinery in nuclear power plants (NPPs) using power line signal analysis is suggested in this work. The primary goal of this work is to improve the motor current signature analysis (MCSA) method that has been used as an alternative or supplement of the conventional vibration monitoring system (VMS). Through this work, the integrated system using both modulated flux density model (MFDM) and rotating flux model (RFM) is proposed. The MFDM is based on the fact that the major mechanical vibration of rotating machines can be normalized to the motor air-gap eccentricity and the modulation of air-gap flux density. Therefore, if the major defect such as bearing defect or the shaft deformation is present, it is identifiable through the power line signal resulting from the modulated magnetic density. Moreover, the broken rotor bar state or rotor eccentricity due to electrical imbalance can be analyzed using the RFM. The other important feature of this system is an automated abnormality detection and diagnosis algorithm. It is possible to diagnose the abnormality without relying on experts in NPPs. The verification is done through varying load/torque test experiment as well as via computer simulation in this work. The experimental results show that they are in good agreement with the simulated results.

Thermooptic 2&amp;gt;tex&amp;lt;$,times,$&amp;gt;/tex&amp;lt;2 Asymmetric Digital Optical Switches With Zero-Voltage Operation State

Thermooptic 2/spl times/2 switches with zero-voltage operation state are demonstrated. The devices made of ultraviolet curable fluorinated polymer are composed of four asymmetric digital optical switches and designed for bar-state operation with initial zero-voltage state. This zero-voltage operation is essential for protection switching in optical networks. The crosstalks of initial bar and cross states are more than 40 dB. The insertion loss and the polarization-dependent loss of the device are less than 1.8 and 0.1 dB for both states, respectively. The power consumption is about 350 mW. The wavelength and temperature dependences of the insertion loss are less than 0.3 dB.

防錆剤混入ポリマーセメントモルタルによる塩害劣化コンクリート中の鉄筋の防食効果

In Japan, the polymer-modified cement mortar (PCM) with the corrosion inhibitor has often been used as repair materials for deteriorated reinforced concrete structures due to the chloride-induced steel corrosion. In this study, the reinforced concrete specimens with two levels of chloride content were prepared and exposed to wet and dry cycles in the chamber for a long period to clarify the macro-cell corrosion of steel bar in the concrete. The effectiveness of the type and dosage of corrosion inhibitor, LiNO2 or Ca(NO2)2, in PCM and the degree of chipping around steel bars in repair work in preventing the steel corrosion in concrete were comparatively investigated by means of electro-chemical measurements such as linear polarization resistance and AC impedance methods.From the experimental results, it was found that PCM with both corrosion inhibitors of LiNO2 and Ca(NO2)2 had almost the same effect in preventing the steel corrosion when their NO2- molecular ratio to Cl- was constant, and that the chipping and patching work beyond steel bars was more effective in restoring the passive state of steel bars. Furthermore, both the linear polarization resistance and the AC impedance methods were very useful as a nondestructive inspection method for estimating the corrosion behavior of steel bars in repaired and unrepaired concrete with PCM.