Efficient completeness inspection using real-time 3D color reconstruction with a dual-laser triangulation system

In this chapter, we present the final system resulting from the European Project \u201d3DComplete\u201d aimed at creating a low-cost and flexible quality inspection system capable of capturing 2.5D color data for completeness inspection. The system uses a single color camera to capture at the same time 3D data with laser triangulation and color texture with a special projector of a narrow line of white light, which are then combined into a color 2.5D model in real-time. Many examples of completeness inspection tasks are reported which are extremely difficult to analyze with state-of-the-art 2D-based methods. Our system has been integrated into a real production environment, showing that completeness inspection incorporating 3D technology can be readily achieved in a short time at low costs

A Study of Voltage-Mode and Current-Mode Filters Using Modified Current Feedback Operational Amplifier

Abstract A Study of Voltage-Mode and Current-Mode Filters Using Modified Current Feedback Operational Amplifier Xin Cui There is a prevalent use of current-mode (CM) circuit techniques in analog integrated circuit design, in view of the fact that CM circuits offer certain advantages over voltage-mode (VM) circuits in terms of certain performance parameters such as propagation delay, dynamic range, and bandwidth. The characteristics of a CM circuit make it not so vulnerable to the current demands of IC design trends, such as continuously decreased size and lower DC supply voltages. Therefore, some active devices that could be exploited in both CM and VM circuits have drawn a lot of attention, such as the second generation current conveyor (CCII) and operational transconductance amplifier (OTA). However, a large amount of effort has been made on VM circuits due to their dominant form of signal processing in analog circuit design for the past several decades. The concept of network transposition, introduced by Bhattacharyya and Swamy as early as in 1971, is a powerful technique to convert a VM circuit to a CM one and vice-versa, with little physical circuit alteration and retaining the same performance as its voltage-mode counterpart. It is especially attractive in transforming those circuits that employ active devices which are transposes of themselves, such as OTA or CCII-. Recently, it has been shown in the literature that a new active element, the modified current feedback operational amplifier (MCFOA), is also its own transpose, and hence can be used to design both VM and CM circuits. It is also known that using the same MCFOA, four equivalent realizations are possible for synthesizing a VM filter function, and further, corresponding four CM filter realizations can be obtained utilizing transposition. However, no detailed study has been conducted with regard to the relative performance of the four equivalent VM structures or the corresponding four CM structures, particularly from the point of view of the non-idealness or the parasitic effects of MCFOA on the performance. This thesis presents a thorough study on band-pass filter (BPF) and notch filter (NF) implemented with MCFOA both in the voltage-mode and their transposed current-mode counterparts. The transfer functions of the four configurations of voltage-mode circuits, as well as that of the current-mode circuits, should be the same when the MCFOA is ideal. However, in practice, they are influenced by parasitic parameters. Accordingly, the performances of the band-pass and notch filters are influenced remarkably by the parasitic parameters of the active device, namely, MCFOA, especially the parasitic resistances for low frequency applications. These effects are studied by comparing the theoretical and SPICE simulation results of the four configurations of the voltage- and current-mode BPF and NF using non-ideal MCFOA. In addition, an improved MCFOA that reduces the effect of parasitic resistances is proposed. Performance of BPF and NF are compared among the four configurations of voltage- and current-mode circuits using the improved MCFOA. They are also compared with those using the original version of MCFOA. It is shown that the proposed MCFOA yields several improvements on the performance of both VM and CM BPFs, such as more attenuation at the low frequencies, and drastic reduction in the ω_p and Q_p errors. Based on the fact that MCFOA is composed of two CCIIs (CCII+ and CCII-), and FTFN can be realized with minor modifications of CCII-, it is natural to compare the performance of BPF using CCII- and FTFN with that using MCFOA. Thus, BPF using CCII- and FTFN and their transposed circuits are also studied. As mentioned earlier, CCII- is its own transpose. However, FTFN does not have a proposed admittance or a hybrid matrix for us to find its transpose. An attempt to find the admittance matrix of FTFN is explored in this thesis. The results show that FTFN can be used as its own transpose only under ideal conditions. Comparisons of performance of BPFs using the original MCFOA, the proposed MCFOA, and CCII-, as well as among their transposes, are presented. It is shown that BPF using the proposed MCFOA exhibits the best performance

Achieving Fast Reconnection in Resistive MHD Models via Turbulent Means

Astrophysical fluids are generally turbulent and this preexisting turbulence must be taken into account for the models of magnetic reconnection which are attepmted to be applied to astrophysical, solar or heliospheric environments. In addition, reconnection itself induces turbulence which provides an important feedback on the reconnection process. In this paper we discuss both theoretical model and numerical evidence that magnetic reconnection gets fast in the approximation of resistive MHD. We consider the relation between the Lazarian & Vishniac turbulent reconnection theory and Lapenta's numerical experiments testifying of the spontaneous onset of turbulent reconnection in systems which are initially laminar.Comment: submitted to Nonlinear Processes in Geophysic

Conceptual design of a fleet of autonomous regolith throwing devices for radiation shielding of lunar habitats

The National Aeronautics and Space Administration (NASA) in conjunction with Universities Space Research Association (USRA) has requested that the feasibility of a fleet of regolith tossing devices designed to cover a lunar habitat for radiation protection be demonstrated. The regolith, or lunar soil, protects the lunar habitat and its inhabitants from radiation. Ideally, the device will operate autonomously in the lunar environment. To prove the feasibility of throwing regolith on the Moon, throwing solutions were compared to traditional, Earth-based methods for moving soil. Various throwing configurations were investigated. A linear throwing motion combined with a spring and motor energizing system proved a superior solution. Three different overall configurations for the lunar device are presented. A single configuration is chosen and critical parameters such as operating procedure, system volume, mass, and power are developed. The report is divided into seven main sections. First, the Introduction section gives background information, defines the project requirements and the design criteria, and presents the methodology used for the completion of this design. Next, the Preliminary Analysis section presents background information on characteristics of lunar habitats and the lunar environment. Then, the Alternate Designs section presents alternate solutions to each of the critical functions of the device. Fourth, a detailed analysis of throwing the regolith is done to demonstrate its feasibility. Then, the three overall design configurations are presented. Next, a configuration is selected and the conceptual design is expanded to include system performance characteristics, size, and mass. Finally, the Conclusions and Recommendations for Future Work section evaluates the design, outlines the next step to be taken in the design process, and suggests possible goals for future design work

LSA project technology development update

The state of low cost solar array technology is discussed. The goal of achieving $500/kW by 1986 is also discussed

Overall requirements for an advanced underground coal extraction system

Underground mining systems suitable for coal seams expoitable in the year 2000 are examined with particular relevance to the resources of Central Appalachia. Requirements for such systems may be summarized as follows: (1) production cost; (2)miner safety; (3) miner health; (4) environmental impact; and (5) coal conservation. No significant trade offs between production cost and other performance indices were found

Unity / variable gain voltage - mode / current - mode first - order all - pass filters using single Dual - X second generation current conveyor

In this paper, two new general topologies for realizing voltage-mode (VM)/current-mode (CM) first-order all-pass filter transfer functions (TFs) are presented. The proposed topologies use single dual-X second-generation current conveyor (DXCCII) and three impedances Z(1), Z(2) and Z(3). Based on the selection of Z(1), Z(2) and Z(3), new VM and CM all-pass filters with unity or variable gains are obtained. The proposed VM/CM filters have high-input/high-output impedances which provide easy cascading at their input/output terminals, respectively. Non-ideal gain and parasitic impedance effects, associated with actual DXCCII implementation, on the performance of the developed topologies are also included. Finally, simulation program with integrated circuit emphasis (SPICE) simulation results based on level 49, 0.25 mu m TSMC complementary metal-oxide-semiconductor (CMOS) technology parameters are given to confirm the theory

Automaattisen varastointi- ja keruujärjestelmän ohjausperiaatteet

Automated storage and retrieval systems (AS/RS) are popular for storing semi-fast moving items in distribution centers. They are costly systems whose design involves many critical decisions, which affect the overall performance of the system. This work is focused on the crane control policies of a double-deep dual-shuttle AS/RS. The goal of the thesis is to find out how operating performance of a crane can be improved with storage location assignment, dwell-point positioning and request sequencing. Alternative control rules were developed based on AS/RS literature and tested against those implemented by the supplier of the system. The comparison was carried out with a discrete-event simulation tool, which was built as a part of the thesis. The system was simulated under two different workload scenarios and rack fill levels. The simulation results indicate that sequencing and cycle formation algorithms can have a significant effect on system throughput in periods of high utilization. The effect was found larger with the lower 70 % fill level. The linear programming sequencing algorithm developed in this thesis was found to reduce the average cycle time by 5.3 % compared to the algorithm used by the supplier. In the on-shift scenario, the optimal dwell point strategy could reduce the average crane response time by 10 % compared to the policy used by the supplier. However, this difference was not noticeable when the average request turnover time was used as a measure.Jakelukeskuksissa yleiset hyllystöhissijärjestelmät ovat kalliita investointeja. Niiden keräilytehoa voidaan osaltaan parantaa tehostamalla varastohissin ohjausmenetelmiä. Tämän diplomityön tutkimuksen kohteena on hyllystöhissijärjestelmä, jossa on tuplasyvät hyllyt sekä hissi, jolla on kahden laatikon kantokapasiteetti. Työn tavoitteena oli selvittää, miten järjestelmän suorituskykyä voidaan parantaa hyllypaikkojen allokoinnin, hissin odotuspaikan valinnan, sekä hissitehtävien sekvensoinnin avulla. Järjestelmätoimittajan ohjausperiaatteiden hyvyyttä arvioitiin vertaamalla niitä kirjallisuuden pohjalta kehitettyihin ohjausmenetelmiin. Ohjausten vertailu tehtiin simulointityökalulla, joka rakennettiin työn aikana. Testiskenaarioissa simuloitiin järjestelmää kahdessa eri kuormitustilanteessa ja kahdella eri täyttöasteella. Simulointitulosten perusteella sekvensointi- ja syklinmuodostusalgoritmeilla huomattiin olevan merkittävä vaikutus tilanteissa, joissa hissillä on tehtäväjonoja. Vaikutus oli suurempi matalammalla 70 % täyttöasteella. Työssä kehitetty sekalukuoptimointiin perustuva sekvensointialgoritmi lyhensi keskimääräistä sykliaikaa 5,3 % toimittajan käyttämään algoritmiin verrattuna. Matalan käyttöasteen skenaariossa optimaalisen odotuspaikan valinta lyhensi hissin liikkumisaikaa seuraavan tehtävään 10 %, mutta ero oli käytännössä olematon, kun mittarina käytettiin keskimääräistä aikaa tehtävän saapumisesta sen suorittamiseen

Performance evaluation of shuttle-based storage and retrieval systems using discrete-time queueing network models

Shuttle-based storage and retrieval systems (SBS/RSs) are an important part of today‘s warehouses. In this work, a new approach is developed that can be applied to model different configurations of SBS/RSs. The approach is based on the modeling of SBS/RSs as discrete-time open queueing networks and yields the complete probability distributions of the performance measures