Fringe Projection Profilometry in Production Metrology: A Multi-Scale Comparison in Sheet-Bulk Metal Forming

Fringe projection profilometry in combination with other optical measuring technologies has established itself over the last decades as an essential complement to conventional, tactile measuring devices. The non-contact, holistic reconstruction of complex geometries within fractions of a second in conjunction with the lightweight and transportable sensor design open up many fields of application in production metrology. Furthermore, triangulation-based measuring principles feature good scalability, which has led to 3D scanners for various scale ranges. Innovative and modern production processes, such as sheet-bulk metal forming, thus, utilize fringe projection profilometry in many respects to monitor the process, quantify possible wear and improve production technology. Therefore, it is essential to identify the appropriate 3D scanner for each application and to properly evaluate the acquired data. Through precise knowledge of the measurement volume and the relative uncertainty with respect to the specimen and scanner position, adapted measurement strategies and integrated production concepts can be realized. Although there are extensive industrial standards and guidelines for the quantification of sensor performance, evaluation and tolerancing is mainly global and can, therefore, neither provide assistance in the correct, application-specific positioning and alignment of the sensor nor reflect the local characteristics within the measuring volume. Therefore, this article compares fringe projection systems across various scale ranges by positioning and scanning a calibrated sphere in a high resolution grid

Performance analysis of Message Passing Interface collective communication on intel xeon quad-core gigabit ethernet and infiniband clusters

The performance of MPI implementation operations still presents critical issues for high performance computing systems, particularly for more advanced processor technology. Consequently, this study concentrates on benchmarking MPI implementation on multi-core architecture by measuring the performance of Open MPI collective communication on Intel Xeon dual quad-core Gigabit Ethernet and InfiniBand clusters using SKaMPI. It focuses on well known collective communication routines such as MPI-Bcast, MPI-AlltoAll, MPI-Scatter and MPI-Gather. From the collection of results, MPI collective communication on InfiniBand clusters had distinctly better performance in terms of latency and throughput. The analysis indicates that the algorithm used for collective communication performed very well for all message sizes except for MPI-Bcast and MPI-Alltoall operation of inter-node communication. However, InfiniBand provides the lowest latency for all operations since it provides applications with an easy to use messaging service, compared to Gigabit Ethernet, which still requests the operating system for access to one of the server communication resources with the complex dance between an application and a network

An Open, Programmable, Multi-vendor 5G O-RAN Testbed with NVIDIA ARC and OpenAirInterface

The transition of fifth generation (5G) cellular systems to softwarized, programmable, and intelligent networks depends on successfully enabling public and private 5G deployments that are (i) fully software-driven and (ii) with a performance at par with that of traditional monolithic systems. This requires hardware acceleration to scale the Physical (PHY) layer performance, end-to-end integration and testing, and careful planning of the Radio Frequency (RF) environment. In this paper, we describe how the X5G testbed at Northeastern University has addressed these challenges through the first 8-node network deployment of the NVIDIA Aerial Research Cloud (ARC), with the Aerial SDK for the PHY layer, accelerated on Graphics Processing Unit (GPU), and through its integration with higher layers from the OpenAirInterface (OAI) open-source project through the Small Cell Forum Functional Application Platform Interface (FAPI). We discuss software integration, the network infrastructure, and a digital twin framework for RF planning. We then profile the performance with up to 4 Commercial Off-the-Shelf (COTS) smartphones for each base station with iPerf and video streaming applications, measuring a cell rate higher than 500 Mbps in downlink and 45 Mbps in uplink.Comment: 6 pages, 9 figures, 4 table

Synchrophasor Based Islanding & Open phase fault Protection in Distribution Systems

With the rapid growth of renewable energy resources, energy efficiency initiatives, electric vehicles, energy storage, etc., distribution systems are becoming more complex such that conventional protection, control, and measurement infrastructure – typically concentrated at the main substation, with little to no access to information along the feeder – cannot maintain the reliability of the system without some sort of additional protection, control and measurement functionalities. As an example, a dedicated communication channel for carrying the transfer trip signal from the substation to the Point of Common Coupling (PCC) to prevent islanding operation of alternative resources, has been a requirement for many utilities. In the transformation of the distribution system from a simple radial system to a bidirectional energy flow network, integration of many intelligent devices and applications will also be required. Thus, this situation calls for investment in communication infrastructure, and augmentation of protection, control, and measurement functionalities. The value of power system communication technologies such as synchrophasor measurement technology – which includes the Phasor Measurement Unit (measuring and providing voltage and current phasors in the real time via communication), communication infrastructure, and Phasor Data Concentrator (PDC) – is being recognized through large-scale deployments around the world. However, these implementations are predominantly limited to some monitoring-type applications and are being realized primarily in transmission systems and bulk power systems (≥100 kV), where performance requirements are much more stringent compared to distribution systems. So contrary to transmission systems, the current status of synchrophasor measurement technology can be utilized to its full extent in distribution systems, as shown in current research for anti-islanding and open-phase faults in the distribution feeder protection application, where the number of PMUs and performance required is somewhat lower than the bulk of power energy. Thus, the opportunity to invest in the implementation of synchronized measurement technology in distribution system is timely as it can be coordinated with other investments in feeder modernization, distributed generation (DG) integration, and infrastructure enhancements that are underway, including “smart grid” initiatives. In the first use case of this research, the behavior of the major DG types during islanding is studied through accurate transient modeling of utility type distribution systems using PSCAD-EMTDC and MATLAB. The study proposes augmentation of PMU-based solutions to the current passive islanding protection elements, such as voltage and frequency, and improving the non-detection zone of the passive elements by adapting their settings based on normal loading conditions at closest known instant prior to the fault or islanding occurrence. The solution proposes a system architecture that requires one PMU at each PCC bus and in the main substation. The communication aspect is based on the IEC 6850-90-5 report, where the PMU can subscribe directly to the data stream of the remote PMUs such that the need for PDCs in this application is eliminated, yielding better performance. In the second use case, an open-phase fault – a major concern for distribution utilities from safety of public and equipment perspective – has been studied. Clearing the open-phase fault without identifying the type of fault could result in an attempt by the recloser to reenergize the downed wire; conversely, an undetected open-phase fault could initiate ferro-resonance, thereby stressing equipment and increasing the risk to public safety, both urban and rural. This work discusses comprehensive analysis of symmetrical components of various types of open-phase faults in the distribution feeder with the presence of distributed generators (DGs) and proposes the use of phasor measurement data located at substation and PCC to identify the open-phase fault. The proposed algorithm relies on the rate of change of the various current and voltage sequence components. In the study conducted, the utility type feeder and substation are modeled in PSCAD-EMTDC, and different types of open-phase fault and shunt faults are studied to verify the dependability and security of proposed algorithm

On Iterative Pre‐Compensation of 3D Laser‐Printed Micro‐Optical Components Using Confocal‐Optical Microscopy

State-of-the-art 3D two-photon laser printing systems already use pre-compensation algorithms to reduce systematic deviations between the printed and the targeted structures. Nevertheless, the remaining deviations are often still larger than the uncontrollable or “statistical” deviations. In principle, it is straightforward to correct for systematic deviations by measuring the difference between printed structure and target and by subtracting the difference from the first target to obtain the next-iteration target. However, in reality, one faces several issues such as noise and systematic errors of the characterization measurement itself, as well as unwanted translations and rotations between the coordinate systems of the characterization setup and the printer, respectively. Two examples of printed structures requiring sub-micrometer accuracy are considered, a large 1D micro-lens array and a specific diffractive optical element. For both, the device performance before the pre-compensation workflow described herein is insufficient for the targeted application and has become sufficient after this workflow. The workflow involving optimizations using cross-correlations with confocal-optical-microscopy data is documented by an open-access program (available via GitLab). This program includes an easy-to-use graphical user interface so that other researchers can immediately profit from it

Master of Science

thesisWhen applied at the right time, Hot Mix Asphalt (HMA) Thin Lift Treatments (TLTs) extend the life of flexible pavements. Correct application depends largely upon pavement condition and rate of deterioration. State Highway Agencies (SHAs) utilize an Open Grade Surface Course (OGSC), Dense Grade Asphalt (DGA), and Stone Matrix Asphalt (SMA) for TLTs. No criteria currently exist to select the best performing mix for factors such as traffic, climate, previous road conditions, and prior treatment methods. Additionally, TLT performance is largely dependent upon local climate conditions and individual state Pavement Management Systems (PMSs). Thus, performance evaluation needs to be done at the local level. This study assessed the early performance of TLTs in Utah by measuring surface cracking within the first two years of service life. This study evaluated 14 TLTs, consisting of eight OGSC, four DGA, and two SMA mixes. Pavement Condition Indices (PCIs), deterioration rate, failure thresholds, and expected design lives identified five early failures. Four of five of these failures resulted from cold temperature thermal cracking. A comparison made from local TLTs to national TLTs, monitored through the Federal Highway Administration’s (FHWA) Long Term Pavement Project, showed a much higher failure rate for the nationally treated roads of 87% to 36%. Cold-temperature related cracking was the predominant early distress type found, both locally and nationally

Optimizing Attitude Control Systems

This paper discusses a practical approach to attitude control system mechanization. Previous efforts reported in the literature have either resulted in systems too complex to mechanize or have not considered the problem in enough of its aspects to make the work meaningful. The classical control optimization techniques are briefly summarized and a critique of these methods is given. The solutions obtained with the classical techniques are either open loop, which is unsatisfactory from an attitude control standpoint, or they are closed loop. These closed loop solutions in general may require measuring all of the system variables, which may not be possible, or they may be far too complex to mechanize. In the proposed approach, called specific optimal control, sensor and actuator characteristics are given and the form of the controller is chosen. Controller parameters are then chosen so as to minimize some performance index. Three analytical methods being developed to perform this optimization are hill climbing, two point boundary value problem formulation, and differential approximation. Each of these methods are discussed. Numerical examples showing the application of these techniques are given in a reference

A smart voltage and current monitoring system for three phase inverters using an android smartphone application

In this paper, a new smart voltage and current monitoring system (SVCMS) technique is proposed. It monitors a three phase electrical system using an Arduino platform as a microcontroller to read the voltage and current from sensors and then wirelessly send the measured data to monitor the results using a new Android application. The integrated SVCMS design uses an Arduino Nano V3.0 as the microcontroller to measure the results from three voltage and three current sensors and then send this data, after calculation, to the Android smartphone device of an end user using Bluetooth HC-05. The Arduino Nano V3.0 controller and Bluetooth HC-05 are a cheap microcontroller and wireless device, respectively. The new Android smartphone application that monitors the voltage and current measurements uses the open source MIT App Inventor 2 software. It allows for monitoring some elementary fundamental voltage power quality properties. An effort has been made to investigate what is possible using available off-the-shelf components and open source software