Process Monitoring Control Research Articles

Integration of sparse singular vector decomposition and statistical process control for traffic monitoring and quality of service improvement in mission-critical communication networks

Mission-Critical Communication Networks (MCCNs) are wireless networks whose malfunction can cause significant problems. The nature of MCCNs puts an extremely high standard on the Quality of Service (QoS). QoS assurance starts from monitoring and change/anomaly detection of network packets data. This problem has been primarily studied by the research community of communication networks, in which the existing methods fall short for providing a privacy-preserving, minimum-disruption, global monitoring tool. Another relevant research area is Multivariate Statistical Process Control (MSPC), in which generic methods have been developed for monitoring high-dimensional data streams. These methods do not account for the special data distribution and correlation structure of packet streams. Nor are they efficient enough to suit real-time analytics in MCCNs. We propose a method called Sparse Singular Value Decomposition (SSVD)-MSPC. SSVD-MSPC addresses the aforementioned limitations and additionally provides key capabilities toward QoS improvement, including monitoring, fault identification, and fault characterization. Extensive case studies are conducted for MCCNs that experience faults of different magnitudes and various temporal shapes. SSVD-MSPC achieves good performance across the different settings in comparison with existing methods.

Direct monitoring of hole damage in carbon fibre-reinforced polymer (CFRP) composites

Carbon fibre-reinforced polymer (CFRP) composite laminates have good specific material properties, these composites are therefore widely used by the high tech industries. Machining operations are often necessary in order to achieve dimensional requirements. However, CFRP is a difficult-to-cut material due to its non-homogenous and anisotropic features and the strong wear-effect of carbon fibres on the cutting tool. Increasing hole numbers causes the increase of cutting edge radius of the cutting tool, therefore hole damages (uncut fibres, delamination etc.) occur more often. The main objective of the present paper is to minimize uncut fibres in CFRP using direct monitoring of hole damage. Firstly, numerous orbital drilling experiments were conducted and the characteristics of uncut fibres were analysed. Secondly, the orbital drilling experiments were repeated with direct monitoring of uncut fibres and process control was applied in order to decrease the size of the burr area. Results show that hole damage decreased with the application of the used process control.

Specialists accounting in audit committees and their role in corporate governance

The new act on statutory auditors, audit forms and public oversight, which came into force in the first half of 2017, introduced important changes related to activities of audit com-mittees supervisor board in public-interest entities. The implemented regulations strengthened the role of audit committees in monitoring of financial statements, audit process and internal control, and choice of audit firm. The Act clearly defined the profes-sional competencies that are needed by the members of an audit committee. One of them should have knowledge of the branch, and at least one should have knowledge in ac-counting or in financial audit. This requirement will make substantive supervision better, and the financial market participants will trust published information more. The aim of the article is to present the role of accounting specialists, when they are the members of an audit committee. The article refers to the kinds of activities, with widely understood interest of the company and shareholders.

Development of a Field Laboratory for Monitoring of Fecal-Sludge Treatment Plants

In urban humanitarian-aid operations, safe treatment of fecal sludge is highly important. While currently field-deployable fecal-sludge treatment plants are being developed, field-ready analytical equipment for process-control and public health monitoring is missing. Within the Microbial Sludge Quality project, a field laboratory was developed. A minimum set of parameters for the considered processes was developed through literature research. The analytical methods were tested on their field applicability and, if necessary, modified. The following methods were modified for field use: bacteriological analysis (sample homogenization and counting), chemical oxygen demand (sample digestion), volatile fatty acid–alkalinity titration (redesigned test setup), total solids (redesigned test setup), and ammonia determination (redesigned test setup). For bacteriological analysis, chemical oxygen demand, and total solids the modifications lead to highly comparable analytical results. The results obtained by the field methodology for volatile fatty acid–alkalinity titration and ammonia determination were sufficient for field-process monitoring; however, they did not correlate as well. To enable rapid startup of the laboratory during humanitarian-aid missions, it was developed to include analytical and support equipment. The usage of the developed laboratory should allow close-in-time process monitoring and public-health assessments of fecal-sludge treatment plants.

Application of statistical process control for spotting compliance to good pharmaceutical practice

For the release of pharmaceutical products into the drug market; most of the pharmaceutical companies depend on acceptance criteria - that are set internally, regulatory and/or pharmacopeially. However, statistical process control monitoring is underestimated in most quality control in cases; although it is important not only for process stability and efficiency assessment but also for compliance with all appropriate pharmaceutical practices such as good manufacturing practice and good laboratory practice, known collectively as GXP. The current work aims to investigate two tablet inspection characteristics monitored during in-process control viz. tablet average weight and hardness. Both properties were assessed during the compression phase of the tablet and before the coating stage. Data gathering was performed by the Quality Assurance Team and processed by Commercial Statistical Software packages. Screening of collected results of 31 batches of an antibacterial tablet - based on Fluoroquinolone -showed that all the tested lots met the release specifications, although the process mean has been unstable which could be strongly evident in the variable control chart. Accordingly, the two inspected processes were not in the state of control and require strong actions to correct for the non-compliance to GXP. What is not controlled cannot be predicted in the future and thus the capability analysis would be of no value except to show the process capability retrospectively only. Setting the rules for the application of Statistical Process Control (SPC) should be mandated by Regulatory Agencies.

Beacon advertising in an IEEE 802.15.4e TSCH network for space launch vehicles

Which wireless technology is able to meet the requirements of space launch vehicles in terms of latency, throughput and robustness? The IEEE 802.15.4e amendment has been designed to meet such requirements. More specifically, the Time Slotted Channel Hopping (TSCH) mode has been designed for industrial automation, process control and equipment monitoring. In this paper, we focus on the time needed by a joining node to detect beacons advertising the TSCH network. An Enhanced beacon is a TSCH frame that contains information on synchronization, channel hopping and timeslot used in the advertised network. However, the advertising policy is left unspecified by the IEEE 802.15.4e standard and is under the responsibility of a layer upper than the MAC one. Since beacons are broadcast, they are lost in case of collisions.The main problem is how to avoid such collisions?In this paper, we propose a Deterministic Beacon Advertising Algorithm, called DBA. The goal of DBA is to ensure that beacons are transmitted on all frequencies used by the TSCH network, regularly and without collision. With DBA, the exact value for the maximum time for a joining node to detect a beacon can be computed easily. We use the NS3 Simulator to evaluate this time as well as the number of message losses, considering different network topologies (star or multihop). We compare the performance of DBA with that of two algorithms existing in the state of the art.

RES-Q-Trace: A Mobile CEAS-Based Demonstrator for Multi-Component Trace Gas Detection in the MIR.

Sensitive trace gas detection plays an important role in current challenges occurring in areas such as industrial process control and environmental monitoring. In particular, for medical breath analysis and for the detection of illegal substances, e.g., drugs and explosives, a selective and sensitive detection of trace gases in real-time is required. We report on a compact and transportable multi-component system (RES-Q-Trace) for molecular trace gas detection based on cavity-enhanced techniques in the mid-infrared (MIR). The RES-Q-Trace system can operate four independent continuous wave quantum or interband cascade lasers each combined with an optical cavity. Twice the method of off-axis cavity-enhanced absorption spectroscopy (OA-CEAS) was used, twice the method of optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS), respectively. Multi-functional software has been implemented (i) for the general system control; (ii) to drive the four different laser sources and (iii) to analyze the detector signals for concentration determination of several molecular species. For the validation of the versatility and the performance of the RES-Q-Trace instrument the species NO, N2O, CH4, C2H4 and C3H6O, with relevance in the fields of breath gas analysis and the detection of explosives have been monitored in the MIR with detection limits at atmospheric pressure in the ppb and ppt range.

Closed loop control system for dough fermentation based on image processing

AbstractDespite the importance of the proofing process in baking industry, no online measurement system is available so far, which can supervise this process step. This article presents the application of a model‐based tuned PID controller to the proofing process in bread baking. The work includes developing an on‐line monitoring system in order to measure volume evaluation of dough pieces during the proofing process and applying the corrective actions to minimize the size variation caused by alteration in amount of yeast added to the ingredients. The controller was tuned by an optimization method. For this purpose, a mathematical model representing the volume evaluation of dough pieces during proofing was identified, which allows an off‐line search for optimal parameters of the controller. The application of the proposed control strategy to an actual proofing chamber for controlling dough leavening during the proofing process was found to be successful.Practical applicationsBesides judging the right amount of proofing time, which is always challenging in the baking industry, alteration in ingredients and different starting states of the dough (normal dough frozen dough or thawed dough) will influence the required time for the proofing process. Any changes in time requirements in the process steps creates a backlog in the whole process, which will lead to inefficient manufacturing and low product quality. Online monitoring and automation process control of the proofing process is an alternative method to overcome these problems. The present research introduces an automated control system based on machine vision for controlling the proofing process in the baking industry. The automated control system is able to reduce the need for close monitoring and process adjustments by human operators, which leads to enhanced productivity and constant high product quality.

Utility of optical heterodyne displacement sensing and laser ultrasonics as in situ process control diagnostic for additive manufacturing

An in situ process control monitor is presented by way of experimental results and simulations, which utilizes a pulsed laser ultrasonic source as a probe and an optical heterodyne displacement meter as a sensor. The intent is for a process control system that operates in near real time, is nonintrusive, and in situ: A necessary requirement for a serial manufacturing technology such as additive manufacturing (AM). We show that the diagnostic approach has utility in characterizing the local temperature, the area of the heat-affected zone, and the surface roughness (Ra ∼ 0.4 μm). We further demonstrate that it can be used to identify solitary defects (i.e., holes) on the order of 10 to 20 μm in diameter. Moreover, the technique shows promise in measuring properties of materials with features that have a small radius of curvature. We present results for a thin wire of ∼650 μm in diameter. By applying multiple pairs of probe–sensor systems, the diagnostic could also measure the local cooling rate on the scale of 1 μs. Finally, while an obvious application is used in AM technology, then all optical diagnostics could be applied to other manufacturing technologies.

Online low-field NMR spectroscopy for process control of an industrial lithiation reaction-automated data analysis.

Monitoring specific chemical properties is the key to chemical process control. Today, mainly optical online methods are applied, which require time- and cost-intensive calibration effort. NMR spectroscopy, with its advantage being a direct comparison method without need for calibration, has a high potential forenabling closed-loop process control while exhibiting short set-up times. Compact NMR instruments make NMR spectroscopy accessible in industrial and rough environments for process monitoring and advanced process control strategies. We present a fully automated data analysis approach which is completely based on physically motivated spectral models as first principles information (indirect hard modeling-IHM) and applied it to a given pharmaceutical lithiation reaction in the framework of the European Union's Horizon 2020 project CONSENS. Online low-field NMR (LF NMR) data was analyzed by IHM with low calibration effort, compared to a multivariate PLS-R (partial least squares regression) approach, and both validated using online high-field NMR (HF NMR) spectroscopy. Graphical abstract NMR sensor module for monitoring of the aromatic coupling of 1-fluoro-2-nitrobenzene (FNB) with aniline to 2-nitrodiphenylamine (NDPA) using lithium-bis(trimethylsilyl) amide (Li-HMDS) in continuous operation. Online 43.5 MHz low-field NMR (LF) was compared to 500 MHz high-field NMR spectroscopy (HF) as reference method.

Autocorrelated process control: Geometric Brownian Motion approach versus Box-Jenkins approach

Existing of autocorrelation will bring a significant effect on the performance and accuracy of process control if the problem does not handle carefully. When dealing with autocorrelated process, Box-Jenkins method will be preferred because of the popularity. However, the computation of Box-Jenkins method is too complicated and challenging which cause of time-consuming. Therefore, an alternative method which known as Geometric Brownian Motion (GBM) is introduced to monitor the autocorrelated process. One real case of furnace temperature data is conducted to compare the performance of Box-Jenkins and GBM methods in monitoring autocorrelation process. Both methods give the same results in terms of model accuracy and monitoring process control. Yet, GBM is superior compared to Box-Jenkins method due to its simplicity and practically with shorter computational time.

Wireless Sensor Network over High Altitude Platform

One of Machine Type Communication (MTC) applications is Wireless Sensor Network (WSN). WSN is an intelligent network application system to collect, integrate, and transmit data autonomously. Sensor nodes in WSN, communicate over short distance via a wireless medium and collaborate to accomplish a common task, such as enviroment monitoring, military surveillance and industrial process control. The constraining aspect of WSN usage is the limited power of each sensor node, so energy efficiency becomes an important issue in WSN. Routing is a function in WSN, which consumes a substantial amount of energy. One of the routing protocols that can increase the energy efficiency of WSN is Low Energy Adaptive Clustering Hierarchy (LEACH). In this paper, High Altitude Platform (HAP) is used to replace Base Station (BS) as sink node in WSN. HAP is designed at altitudes of 17, 20 and 22 km. Then WSN over HAP using the LEACH routing protocol evaluated its performance. Performance indicators that we evaluated are engergy consumption, number of dead nodes and total average packets which is sent to HAP. From a series of simulations conducted, the results obtained that the higher the laying of HAP, then the coverage area will be greater. So that the energy consumption will be smaller, the number of dead node less and the avarage of total packet delivered to the HAP will be greater.

Algae optical density sensor for pond monitoring and production process control

Open raceways are one of the principal commercial-scale systems for cultivating algae to produce biofuels and bioproducts. A critical process parameter in such a system is algae cell concentration in the aqueous culture, commonly measured in terms of optical density (OD). A prototype OD sensor exclusively for real-time measurement of algae cell concentration in open ponds was designed, constructed, and tested in a laboratory scale raceway and an open-pond raceway. In the lab test, the sensor OD measurements were highly correlated with spectrometer OD measurements. The OD curve recorded by the sensor clearly showed the diurnal pattern of algae growth associated with the on-off cycle of the lighting system in the lab facility. The test data also clearly highlighted unique cultivation activities such as growth media addition and harvesting. In the open pond raceway test, sensor OD data were also highly correlated with spectrometer-measured OD even though the range of OD variation was significantly less during this test. The OD curve clearly indicated a higher biomass accumulation rate in the pond from late morning to late afternoon than during the rest of the day. These tests of the OD sensor demonstrated its potential to provide accurate real-time algae concentration data in an open pond cultivation system, the type of data that would be necessary for timely management decision-making. This sensor would also eliminate the cost associated with frequently collecting and analyzing samples, making commercial-scale algae production more economically practical. Keywords: microalgae, optical density (OD), open pond raceway, sensor, pond monitoring, circuit design, optoelectronics DOI: 10.25165/j.ijabe.20181101.2839 Citation: Yao Y, Ge Y F, Thomasson J A, Sui R X. Algae optical density sensor for pond monitoring and production process control. Int J Agric & Biol Eng, 2018; 11(1): 212–217.

Statistical process control and strength monitoring of ready-mixed concrete through the application of CUSUM and EWMA control charts: a case study of Ahmedabad and Gandhinagar RMC plants

This research work is an attempt to improve the quality of concrete by implementing statistical process control tools like CUSUM with V-mask and exponentially weighted moving average (EWMA) control charts for ready-mixed concrete (RMC) plants in the Gandhinagar and Ahmedabad regions of India. These tools are used for sensitising the qualitative analysis of concrete in terms of the 28 days cube compressive strength. It has been observed that the RMC plant authorities were using an over-conservative mix design for the grades of concrete produced. This practice resulted in the usage of more cement than that stipulated in the mix design. The usage of higher cement content is wastage of resource. Also, this practice results in adverse side effects like production of more heat of hydration which creates shrinkage cracks. The application of these tools for strength monitoring would result in cost savings of about INR 4.8 million to 7.2 million per annum.

Statistical process control and strength monitoring of ready-mixed concrete through the application of CUSUM and EWMA control charts: a case study of Ahmedabad and Gandhinagar RMC plants

Statistical process control and strength monitoring of ready-mixed concrete through the application of CUSUM and EWMA control charts: a case study of Ahmedabad and Gandhinagar RMC plants

Dependence of {111}-textured Pt electrode properties on TiO2 seed layers formed by thermal oxidation

The Pt/TiO2/SiO2/Si electrode structure prepared using sputter deposition of Ti, conversion of Ti to TiO2 by thermal oxidation, and sputter deposition of Pt was evaluated by using measurements of sheet resistance and X-ray diffraction. Nonlinearity of the reciprocal sheet resistance dependence on thickness revealed a change in the Ti conductivity that was attributed to a change in the Ti microstructure. Upon conversion to TiO2, it was determined that TiO2 exhibits a critical thickness of 32 nm that minimizes normal strain and {100}-textured misorientation and correlates with the onset of the Ti reciprocal sheet resistance nonlinearity. Both the TiO2 {100}-strain and {100}-texture directly affects the {111}-textured growth of Pt deposited at 500 °C. Pt deposited onto TiO2 films with the critical thickness of 32 nm exhibits a maximization of the normal strain relative to bulk Pt and also displays the narrowest distribution of Pt {111}-textured grain misalignment. The results presented show how Ti deposition conditions, TiO2 anneal conditions, and TiO2 thickness combine to modify the Pt electrode structural properties. Additionally, the measurement techniques demonstrated for the Ti, TiO2, and Pt are applicable to process control monitoring as well as standardized comparison of electrode structures used in integrated piezoelectric and ferroelectric devices.

(Invited) How to Integrate MEMS on Foundry-Fabricated CMOS Backplanes

A large variety of new applications for Internet of Things (IoT), Industrie 4.0 and other consumer products are pushing volume and manufacturing of microelectromechanical systems (MEMS) into a new phase. Due to massive use of these sensors and actuators in mobile and industrial applications smaller systems combined with low power consumption and higher versatility are required. MEMS are transducers that sense or control physical, chemical or optical quantities creating devices for applications in the area of 3D-motion tracking, pressure sensing, light shaping or detection of irradiation. The combination of MEMS with an application specific integrated circuit (ASIC) based on CMOS technology enables the entire system to interact with outside world. These ASICs are providing required features such as analog-to-digital conversion, amplification, filtering, information processing and storage as well as communication to the outside world. There are different solutions available to combine MEMS with customized CMOS circuits. One choice known as system-in-package (SiP) is the manufacturing of MEMS and CMOS on separate wafers and its subsequent integration in a multi-chip module using interposer/ rewiring technologies. Key advatanges of this technique are high flexibility, high modularity and a complete decoupled manufacturing of CMOS and MEMS. This enables a rapid development and leads to low development costs. And, there is no impact of different sizes between CMOS and MEMS chip. In order to enhance the integration density, to drive system feature size down, to suppress potential parasitic capacitances and to reduce power consumption an integrated manufacturing on the same substrate is a must and known as system-on-chip (SoC) solution. On one hand this approach can be still realized by a multi-wafer processing and a final integration using bonding technologies. This technology is often named as heterogeneous integration. Key advantage of multi-wafer technology is the possibility to use high-performance MEMS materials such as monocrystalline silicon as actuation/sensing material and its integration on CMOS wafers. Disadvantages are the required alignment accuracies when using a metallic bond or limitation for integration densities when using via-last approach. A more consistent way is a complete monolithic integration of MEMS on CMOS substrates. Especially when large transducer arrays are required (e.g. bolometers, micro-mirror arrays, CMUT arrays) a monolithic integration of MEMS on CMOS is the best solution. All advantages are now on hand – high integration densities, low parasitic capacitances and an effective usage of CMOS area. Fraunhofer IPMS applies surface and bulk micromachining technologies for the integration of MEMS on customized CMOS backplanes. To reduce development costs and time-to-market IPMS combines standard CMOS processes offered from CMOS foundries with a subsequent integration of MEMS part in our MEMS fab. Due to the application specific design of the CMOS backplane this concept allows a perfect match between ASIC and MEMS functionalities. In a typical project flow CMOS and MEMS will be manufactured and tested in parallel to shorten development time. After ASIC design is finished it will be tested using Multi- Project- Wafer run (MPW) in a CMOS foundry. Using these MPW runs a complete characterization of CMOS functionality can be realized in an early project state at low costs. Parallel to CMOS testing an entire process development of MEMS part can be done on passive devices in our MEMS fab. If CMOS and MEMS characterization is completed the MEMS part will be monolithically integrated on these customized CMOS backplanes. But there are still some challenges for the integration of MEMS on foundry fabricated CMOS backplanes, e.g.: Modifications of last CMOS/ interconnect/ ILD layers to realize an appropriate interface to MEMS Clarification of PCM (process control monitoring) test environment, depth of test structures and possible arising contamination issues In-chip surface topology after interconnect processing to define necessary actions to achieve required planarity for further processing Tuning mix-and-match lithography to achieve high overlay accuracies (Picture 1: Reached overlay accuracy between last 0,18µm CMOS and first MEMS layer of about 30- 40nm after correction step using i-line stepper) Required chip design features when using sacrificial layer technology IPMS offers a wide range of surface and bulk micromachining technologies which are particularly suitable for the fabrication of sensors and actuators on pre-fabricated CMOS wafers using monolithic integration. Especially surface micromachining using inorganic sacrificial layer technology allows the realization of rather complex MEMS structures on CMOS backplanes. Based on examples such as spatial light modulators (SLM) and capacitive micromachined ultrasonic transducers (CMUT) we will present solutions for the integration of surface micromachined MEMS on customized CMOS substrates. Figure 1

Fluorescence based real time monitoring of fouling in process chromatography

A real time monitoring of fouling in liquid chromatography has been presented. The versatility of the approach has been proven by successful implementation in three case studies with an error <1%. The first application demonstrates the monitoring of protein A ligand density and foulant concentration for assessing performance of protein A chromatography resin during purification of monoclonal antibodies. The observations have been supported from LC-MS/MS studies that were independently performed. The second application involves monitoring of foulant deposition during multimode cation exchange chromatography based purification of human serum albumin. Finally, in the third application, monitoring of foulants during multimodal hydrophobic interaction chromatography of recombinant human granulocyte colony stimulating factor is demonstrated. In all three cases, it is observed that the fluorescence intensity consistently increases with resin reuse as more foulants are deposited over time. The proposed approach can be readily used for real time monitoring of fouling and process control.

Cyber security of IP-based data communication network for power system operations

With the proliferation of Smart Grid technologies and IP-based Process Control and Condition Monitoring Systems for power system operations, bulk electric system (BES) is now more dependent on real-time information exchange between control centre and remote end Intelligent Electronic Devices (IED's) for monitoring and optimizing the transmission and distribution of electricity. Because of this, there are growing concerns on cyber security issues that brought by these technologies. It was noted that attention has been drawn to the security framework for engineering applications/systems and their own local area network (LAN), but the security and reliability of the communication channels for supporting these applications/system have been taken for granted. This paper summarizes how The Hongkong Electric Co., Ltd. (the Company) has designed and built an IP-based Data Communication Network (DCN) for engineering applications with due consideration on the system security and reliability.

Evolution, modelling and simulation of MEMS PWM pressure sensor employing cantilever switch and SOI diaphragm

There are applications that need pressure sensors which produce easily transmittable digital output and are free from inherent disadvantage of conventional piezoresistive and capacitive pressure sensors. This paper presents a micro electro mechanical systems (MEMS) pressure sensor based on pulse width modulation (PWM) technique. The proposed mechanism converts the applied pressure into equivalent PWM signal with an innovative but simple structure. The mathematical model relating the duty cycle of the PWM output signal and the pressure is derived from basic principles first to explain the sensing mechanism theoretically. Simulation studies conducted to validate the proposed sensing principle not only match the theoretical predictions well but also provide the design guidelines for achieving high sensitivity and least non-linearity. The fabrication process flow for the sensor structures has been also developed and presented. Finally this paper presents a design of a PWM pressure sensor and various studies to evaluate the performance of the sensor. Systematic simulation and theoretical studies show that it is possible to achieve a sensitivity of 6.7 mV/kPa with less than 8 % non-linearity using this approach in addition to getting a digital output. These studies further illustrate that this sensing concept paves the way for fabrication of MEMS pressure sensor that needs no complex signal conditioning electronics. Similarly the direct digital output from the sensor make them suitable for applications like Tire pressure monitoring system and process control automation systems.