Poor Process Control Research Articles

Microbial electrosynthesis with Clostridium ljungdahlii benefits from hydrogen electron mediation and permits a greater variety of products.

Microbial electrosynthesis (MES) is a very promising technology addressing the challenge of carbon dioxide recycling into organic compounds, which might serve as building blocks for the (bio)chemical industry. However, poor process control and understanding of fundamental aspects such as the microbial extracellular electron transfer (EET) currently limit further developments. In the model acetogen Clostridium ljungdahlii, both direct and indirect electron consumption via hydrogen have been proposed. However, without clarification neither targeted development of the microbial catalyst nor process engineering of MES are possible. In this study, cathodic hydrogen is demonstrated to be the dominating electron source for C. ljungdahlii at electroautotrophic MES allowing for superior growth and biosynthesis, compared to previously reported MES using pure cultures. Hydrogen availability distinctly controlled an either planktonic- or biofilm-dominated lifestyle of C. ljungdahlii. The most robust operation yielded higher planktonic cell densities in a hydrogen mediated process, which demonstrated the uncoupling of growth and biofilm formation. This coincided with an increase of metabolic activity, acetate titers, and production rates (up to 6.06 g L-1 at 0.11 g L-1 d-1). For the first time, MES using C. ljungdahlii was also revealed to deliver other products than acetate in significant amounts: here up to 0.39 g L-1 glycine or 0.14 g L-1 ethanolamine. Hence, a deeper comprehension of the electrophysiology of C. ljungdahlii was shown to be key for designing and improving bioprocess strategies in MES research.

Forecasting the research octane number in a Continuous Catalyst Regeneration (CCR) reformer

AbstractGasoline is still one of the most consumed crude oil derivatives in the global market. Its grade is established by the Research Octane Number (RON), which is measured by laboratorial analysis at a lower rate in comparison to process variables. This delay represents a bottleneck to process operation (monitoring, control, and optimization) and quality (less consistency due to poor process control), with impact in the company's bottom line results. In order to mitigate the effects of such delay, we address the problem of predicting RON using real industrial data from a refinery located in Portugal. The dataset was collected at Matosinhos Refinery of Petrogal, SA, during an extended period of operation (2 years). We report the performance of a wide range of state‐of‐the‐art linear and non‐linear methods able to cope with high‐dimensional data, which are assessed through a framework based on Monte Carlo Double Cross‐Validation. Overall, 25 methods and their variants were tested which, to the best of authors’ knowledge, is the largest number of methods ever considered in studies dedicated to the prediction of RON. Furthermore, a ranking system for efficiently comparing the methods is also proposed, facilitating the identification of the top performing ones. According to this methodology, kernel partial least squares and tree‐based ensemble methods stand out among the methods tested, signalling the presence of non‐linear relationships in the datasets.

A technical review of the challenges of powder recycling in the laser powder bed fusion additive manufacturing process

Laser powder bed fusion (L-PBF) is one of the most widely used additive manufacturing techniques for fabrication of components with complex geometries for various industrial applications including aerospace, medical and automotive. The unconsumed powder after part manufacturing is often recovered and recycled to improve process efficiency. However, some of the particles in the recycled powder can have different physical and chemical properties from those in the virgin powder owing to their exposure to the complex environment during the manufacturing process. In addition, some contaminants can be introduced in the recycled powder due to poor process control. A number of studies have been published in the past few years revealing the effects of powder recycling on the build properties. The present work aims to highlight the key phenomena during the manufacturing process that caused degradation to the recycled powder. Further to this, some comments, gaps and areas that deserve further detailed studies are also highlighted.

A Study on Polycyclic Aromatic Hydrocarbon and Heavy Metal Concentrations of Commercial Grilled Meat (Suya) and Smoked Catfish (Clarias gariepinus Burchell, 1822) Fish from South-West, Nigeria

This study was undertaken to assess polycyclic aromatic hydrocarbon (PAH) and heavy metal concentrations of commercial grilled meat (suya) and smoked catfish (Clarias gariepinus Burchell, 1822) from South-West, Nigeria. A total of 100 samples of grilled meat and 100 samples of smoked catfish were collected purposively from five major cities in South-West, Nigeria between July and October, 2019. The samples were analyzed to determine PAH and heavy metal [Lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr), and Arsenic (Ar)] concentrations present in the samples. This study revealed that commercial suya and smoked catfish samples from major cities from South West, Nigeria contained varying concentrations of the following carcinogenic PAHs; Benzo[a]pyrene (B[a]P), Benzo[a]anthracene (B[a]A), Benzo[b]fluoranthene (B[b]FA), Benzo [ghi] perylene (B[ghi]P), and Dibenzo(a,h)anthracene (DB[a,h]A). The concentrations of the PAHs in the samples were very high and above the European Union maximum permissible level of 2.0 µg/kg (0.002 mg/kg) for BaP and 12 µg/kg (0.012 mg/kg) for the sum of 4PAHs (B[a]P + Chr + B[b]F + B[a]A) approved by Commission Regulation (EC) No 1881/2006 of 19 December 2006 as amended by Regulation (EU) No 835/2011 of 19 August 2011 for B[a]P allowed in grilled or smoked meat and fish for human consumption. The high concentrations of carcinogenic PAHs in commercial suya and smoked catfish from major cities in South West, Nigeria above the EU maximum permissible level of 2.0 µg kg−1 may be due to poor process control like high grilling temperature above 100 °C and longer grilling time associated with traditional suya processing and fish smoking in Nigeria. This could have resulted in public health concerns for consumers as carcinogenic PAHs have been linked to cancer. Also, the concentrations of Pb, Cd, Hg, Cr, and Ar in the commercial suya and smoked catfish samples studied were very low below the maximum permissible limits approved by World Health Organization, 2006 for grilled and smoked meat and fish which are Pb (0.3 mg/kg); Cd (0.2 mg/kg), Hg (0.2 mg/kg), and Cr (0.3 mg/kg) and therefore the products may not constitute health risks to consumers.

Hostel (dormitory) restroom floors, an underrated reservoir for transmission of health care-associated multidrug resistant pathogens in Nigeria: A combination of poor disinfection process and infection control

Acquisition of hospital and community-associated methicillin resistant Staphylococcus aureus (MRSA), extended spectrum beta lactamase producing Escherichia coli (ESBL-E. coli) and carbapenemase-producing Klebsiella pneumoniae (CPKP) from dirty environments is widely reported in Nigeria. Restroom floors of congested hostels (dormitories) and high-touch surfaces such as corridors, doors, and wardrobes handles, and hands of restroom users and non-users were studied for the presence of MRSA, ESBL-E. coli and CPKP before and 1 hour after cleaning and disinfection. Surfaces were swabbed with sterile moistened swab sticks, and isolation and identification of S. aureus, E. coli and K. pneumoniae were performed using standard techniques. Methicillin resistance by S. aureus, ESBL production by E. coli and carbapenemase production by K. pneumoniae were determined phenotypically using cefoxitin susceptibility, double disc synergy and modified Hodges tests, respectively. Amplification of blaCTX-M, and blaNDM-1 in ESBL-E. coli and CPKP was performed using PCR. We found that restroom floors were frequently contaminated with MRSA, ESBL-E. coli, and CPKP before and 1 hour after cleaning. High-touch surfaces such as corridors, doors, and wardrobes handles were contaminated with these pathogens, as well as hands of restroom users. The process of floor disinfection was able to reduce the percentage of MRSA, ESBL-E. coli and CPKP by 23.8%, 50%, and 22.2%, respectively. Pathogens from restroom floors and hand of users harbor similar resistant genes. The findings suggest that people with frequent contact with these surfaces can acquire and disseminate the pathogens to others.

Microbial Dynamics in Traditional and Modern Sour Beer Production.

Traditional sour beers are produced by spontaneous fermentations involving numerous yeast and bacterial species. One of the traits that separates sour beers from ales and lagers is the high concentration of organic acids such as lactic acid and acetic acid, which results in reduced pH and increased acidic taste. Several challenges complicate the production of sour beers through traditional methods. These include poor process control, lack of consistency in product quality, and lengthy fermentation times. This review summarizes the methods for traditional sour beer production with a focus on the use of lactobacilli to generate this beverage. In addition, the review describes the use of selected pure cultures of microorganisms with desirable properties in conjunction with careful application of processing steps. Together, this facilitates the production of sour beer with a higher level of process control and more rapid fermentation compared to traditional methods.

Considerations on Protein Stability During Freezing and Its Impact on the Freeze-Drying Cycle: A Design Space Approach.

Freezing is widely used during the manufacturing process of protein-based therapeutics, but it may result in undesired loss of biological activity. Many variables come into play during freezing that could adversely affect protein stability, creating a complex landscape of interrelated effects. The current approach to the selection of freezing conditions is however nonsystematic, resulting in poor process control. Here we show how mathematical models, and a design space approach, can guide the selection of the optimal freezing protocol, focusing on protein stability. Two opposite scenarios are identified, suggesting that the ice-water interface is the dominant cause of denaturation for proteins with high bulk stability, while the duration of the freezing process itself is the key parameter to be controlled for proteins that are susceptible to cold denaturation. Experimental data for lactate dehydrogenase and myoglobin as model proteins support the model results, with a slow freezing rate being optimal for lactate dehydrogenase and the opposite being true for myoglobin. A possible application of the calculated design space to the freezing and freeze-drying of biopharmaceuticals is finally described, and some considerations on process efficiency are discussed as well.

(Invited) Thermal-Expansion Matched and CMOS Fab-Friendly Engineered Substrates Enabling Unmatched Cost, Performance & Application Scale for GaN Devices

GaN is a miracle wide bandgap semiconductor material with unique properties, enabling many critical energy-efficient and novel applications such as LED lighting, next generation of small-size and efficient power devices, high frequency RF electronics, sensors, and more. At the same time, the lack of suitable large diameter and scalable substrates solutions, thereby cost effective and high performance manufacturing platforms, has been slowing down widespread adoption of GaN-based devices for decades, and keeping GaN device manufacturing in small diameter (2-inch, 4-inch, 6-inch) compound semiconductor fabs with limited yield, poor process control and high cost, whereas mainstream semiconductor industry has far moved on to highly automated and cost-efficient 8-inch and 12-inch diameter manufacturing platforms. In this talk, we will be presenting (1) a revolutionary and validated CMOS fab-friendly 8-inch diameter QST® (QROMIS Substrate Technology) substrates, which are scalable to 12-inch, for very high quality (bulk-like) and crack-free GaN epitaxial growth, including enablement of large diameter free-standing GaN substrates via growing very thick GaN epitaxy layers (>100 µm), and (2) QST®-based GaN device results enabling an unmatched cost, performance, and application scale. The QST® substrates, with a compliant Si <111> growth surface, have a thermal expansion coefficient matched to GaN epitaxial layers; and this unique feature alleviates the fundamental challenges in (a) economies of scale, (b) performance scale and (c) applications scale which are inherent to GaN-on-Si, GaN-on-SiC, GaN-on-GaN and other proposed solutions. Various wafer bonding technologies play a key role in large diameter GaN device manufacturing on QST® substrates. Different types of commercial bonding techniques are used in QST® substrate manufacturing, device fabrication and backend processes. In this talk, we will zoom into key wafer bonding techniques and processes which are currently being used (or to be used) in high volume and advanced GaN device manufacturing, such as for LEDs, power and RF devices in lateral, vertical and wafer-level chip scale package forms and architectures. Figure 1

The impact of experimental data quality on computational systems biology and engineering

Abstract: The success of computational methods in systems biology and systems engineering relies on the availability of mathematical models which represent the biological system adequately The process of model development, model analysis and model invalidation is, however, often limited by the availability of suitable experimental data leading to impaired significances of the models. Especially mathematical models build for the purpose of process control, optimization and analysis have to represent and predict the behavior of the system very well. But how to generate experimental data which is suitable for computational systems biology and engineering? In this work we demonstrate that the close connected use of experimental and theoretical methods can be the key for deriving experimental data and mathematical models of a high quality. As a first step the experimental conditions which cause the desired systems behavior have to be identified and maintained. Poor process control strategies or a general lack of control engineering are often the bottleneck, impeding a systematic experimental approach. Here we show, by applying methods from bioengineering, systems biology and control engineering, how an experimental platform can be created which allows to address systems biological questions systematically. The shown approach stabilizes the process around a chosen working point so that the reaction of the system to a defined stimulation of an input can be monitored whilst the remaining process variables are kept constant. In that way dynamic system responses can be assigned to the change of a single input and hierarchical information of complex biological systems are revealed. In this work we use our approach to study the formation of photosynthetic membranes (PM) under microaerobic conditions in Rhodospirillum rubrum.

The Role Of Budget And Budgetary Control On Organisational Performance: A Case Study Of Tahir Guest House, Kano State, Nigeria

Budgeting is an indispensable tool in the hospitality industry-which has profit maximization as its goal and this can only be realized when resources are properly planned and controlled with the required commitment and expertise. Hotel accommodation in Nigeria is facilitated mostly by the corporate sector, with booking for conferences and meetings demand being highest. Whilst there has been rapid growth in the Nigerian hotel industry in the last decade, it is still in its infancy as the National Bureau for Statistics (2013) posited that the hotels and restaurant sub-sector contributes a mere 0.55 per cent to the Gross Domestic product (GDP). However, the major reason for this insignificant contribution to the GDP has been linked to poor budgeting process and internal control within the players in the industry. This paper therefore researched into the role of budget and budgetary control on organizational performance: a case study of Tahir Guest Palace, Kano. The study made use of both the primary and the secondary data. The instrument for the collection of the primary data was the questionnaire administered, while the secondary data was obtained via the financial statements of Tahir Guest Palace from 2007-2012. A total of 278 staff was sampled using the purposive sampling technique, and data obtained was subjected to regression analysis.Result revealed that budget administration, budget target setting and budget process all have significant impact on organizational performance. The research work therefore, recommendthat;(i) the top level management of Tahir guest palace should maintain appropriate standard on budget administration and preparation, and budget process. Specifically, the use of the current budget process on previous budget performance should be emphasized in measuring performance year in year out, as this will enable the management to monitor the organizational growth and or performance as budgeted; (ii) the staff of various cadres at Tahir guest palace should also be allowed to participate in the budget target setting and process to further enhance the organizational performance. If the above recommendations are implementedit will not only increase the organizational performance of Tahir Guest Palace but will also lead to increase in subordinates efforts and task performance.

Advanced Bode Plot Techniques for Ultrasonic Transducers

The Bode plot, displayed as either impedance or admittance versus frequency, is the most basic test used by ultrasonic transducer designers. With simplicity and ease-of-use, Bode plots are ideal for baseline comparisons such as spacing of parasitic modes or impedance, but quite often the subtleties that manifest as poor process control are hard to interpret or are nonexistence. In-process testing of transducers is time consuming for quantifying statistical aberrations, and assessments made indirectly via the workpiece are difficult. This research investigates the use of advanced Bode plot techniques to compare ultrasonic transducers with known “good” and known “bad” process performance, with the goal of a-priori process assessment. These advanced techniques expand from the basic constant voltage versus frequency sweep to include constant current and constant velocity interrogated locally on transducer or tool; they also include up and down directional frequency sweeps to quantify hysteresis effects like jumping and dropping phenomena. The investigation focuses solely on the common PZT8 piezoelectric material used with welding transducers for semiconductor wire bonding. Several metrics are investigated such as impedance, displacement/current gain, velocity/current gain, displacement/voltage gain and velocity/voltage gain. The experimental and theoretical research methods include Bode plots, admittance loops, laser vibrometry and coupled-field finite element analysis.

A Novel Soft Sensor for Real-Time Monitoring of the Die Melt Temperature Profile in Polymer Extrusion

Polymer extrusion is the most fundamental technique for processing polymeric materials, and its importance is increasing due to the rapid growth of worldwide demand for polymeric materials. However, the process thermal monitoring is experiencing several problems resulting in poor process diagnostics and control. Most of the existing process thermal monitoring methods in industry only provide point/bulk measurements, which are less detailed and low in accuracy. Physical thermal profile measurements across the melt flow may not be industrially compatible due to their complexity, access requirements, invasiveness, etc. Therefore, inferential thermal profile monitoring techniques are invaluable for obtaining detailed, accurate, and industrially compatible measurements and, hence, to achieve improved process control. In this paper, a novel soft sensor strategy is proposed to predict the real-time temperature profile across the die melt flow in polymer extrusion for the first time in industry or research. It is capable of determining the melt temperature at a number of die radial positions only based on six readily measurable process parameters. A comparison between the simulation results of the novel melt temperature profile prediction soft sensor and the experimental measurements showed that the soft sensor can predict the real-time melt temperature profile of the die melt flow with good accuracy. Therefore, this will offer a promising solution for making real-time melt temperature profile measurements noninvasively in polymer extrusion, and also, it should be applicable to other polymer processes only with a few modifications. Moreover, this technique should facilitate in developing an advanced process thermal control strategy.

OPTIMIZATION OF CHIPOTLE PEPPER SMOKING PROCESS USING RESPONSE SURFACE METHODOLOGY*

ABSTRACTEffects of smoking time and temperature on optimal chipotle pepper production were evaluated and optimized using the response surface methodology. Batches of red jalapeño peppers were smoked under different temperatures (65.8, 70, 80, 90, 94.1C) and times (0.96, 2, 4.5, 7, 8 h). Afterward, samples were evaluated for moisture, rheological properties and total phenols. Samples were then dried from 80C to between 0.123 and 0.204 kg H2O/kg dry matter and evaluated for rheological properties, texture, rehydration, color and phenols. Phenol content, rehydration ratio, firmness of peppers, and rheological properties and color of puree were affected (P &lt; 0.05) by both temperature and time. Best smoking conditions used temperatures of 74–79C, and times between 8.0 and 7.4 h resulting in viscosities of 5.1–6.5 Pa·s with phenol content of 110–120 mg/kg, rehydration ratios of 3.7–4.1, firmness of 1.27–1.49 N and acceptable color. Smoking time was significantly reduced and quality maintained.PRACTICAL APPLICATIONSChipotle pepper is highly appreciated by consumers because of their aroma and flavor characteristics. Chipotle pepper is obtained by smoking red jalapeño in open ovens, where combustion gases from hardwoods are passed during long times to smoke and dehydrate them. This process has the disadvantage of producing environmental contamination and wide quality variability because of a poor process control. In this study, a correlation of smoking and drying was optimized in order to determine the effect of temperature and smoking time on the physical and chemical characteristics of the chipotle pepper. Additionally, polynomial models are presented for each variable evaluated in the smoking chipotle pepper operation and optimized for the desired quality of the chipotle pepper. This information can be useful to processors because they can achieve a ninefold reduction in the smoking time compared with the traditional smoking processes without affecting the chemical and physical characteristics of chipotle peppers.

Reaction engineering: The supercritical water hydrothermal synthesis of nano-particles

Supercritical water hydrothermal synthesis (scWHS) is a relatively simple and environmentally friendly process for the production of potentially valuable metal oxide nanoparticles. However, it has never found industrial application to date due to poor process reliability, reproducibility and control. This paper presents the conclusions of collaborative work between chemical engineers and chemists that attempts to optimise the reaction engineering of this process, with the goal of reducing or even eliminating these fundamental process flaws. Initial investigations on the mixing in a T-piece highlighted that the environment within the scWHS reactor is highly unusual in terms of conventional reaction engineering because the fluid properties were significantly different in terms of temperature, viscosity and density. This led to the development of an optimised reactor, termed the Nozzle Reactor, which was designed on the basis of Light Adsorption Imaging (LAI) and Computational Fluid Dynamics (CFD) modeling, both of which show excellent mixing mechanics. Light Adsorption Imaging is an image analysis visualization method using fluids of different densities at ambient conditions. Experimental results using the Nozzle Reactor are presented showing how different metal oxide particles can be produced including titania, ceria, zirconia, copper, zinc and silver. The reactor shows a dramatic improvement in process reproducibility (±5 m 2/g for BET surface area) and in reliability such that, given further investigation, will lead to process optimisation. Preliminary evidence suggests that the reactor could eventually lead to the ability to control particle properties, such as size, composition and shape, through the manipulation of process variables.

Significance of controlling crystallization mechanisms and kinetics in pharmaceutical systems

Metastable thermodynamic states are frequently encountered in pharmaceutical systems, in the intentional or unintentional creation of supersaturation, in the crystallization of desired solid-state modifications, and in the control of solid-phase conversions during isolation, manufacturing, storage, and dissolution.1-4 Some examples in which metastable states are encountered include solid solutions, freeze-concentrated solutions, solutions of weak acids or bases exposed to a pH change, solutions prepared by dissolving a solid-state modification with a higher solubility (higher free energy), and residual solutions during filtration, granulation, and drying. Because crystallization provides a way of reducing the free energy of metastable thermodynamic states, the extent to which metastable states can be maintained is determined by the crystallization mechanisms and kinetics.5-16 What is surprising, however, is that despite the important role that crystallization has in process control and in determining solid-phase outcomes, crystallization phenomena are often neglected in the pharmaceutical industry until a problem is encountered. While emphasis is often given to the knowledge of equilibrium phase diagrams with the purpose of identifying the concentration and temperature regions of thermodynamic stability of solid phases, information on crystallization processes can only be obtained by combining studies of thermodynamic properties with kinetic measurements. Cases of unwanted or previously unknown nucleation events abound. Dunitz and Bernstein17 documented cases of “disappearing or elusive polymorphs” that provide evidence for the consequences of poor process control in crystallization of polymorphic systems. The recent shortage in the supply of capsules of the HIV protease inhibitor Norvir (indinavir), due to the sudden formation of a crystalline structure different from the one harvested for months,18 illustrates the decisive role that nucleation mechanisms and kinetics have on crystallization. Nichols and Frampton19 have reported considerable efforts that failed to crystallize the metastable polymorph of paracetamol as described in the initial publication of the crystal structure.20 The critical role of crystallization kinetics in determining the appearance of crystalline modifications is also recognized by the FDA and described in the guidelines for the manufacture of drug substances:21 “Appropriate manufacturing and control procedures (including in-process testing when needed) should be established for the production of the desired solid-state form(s). It should be emphasized that the manufacturing process (or storage condition) is responsible for producing particular polymorphs or solvates; the control methods merely determine the outcome.” Even when the parameters that regulate crystallization phenomena are neglected, the illusion of process control is motivated by a crystallization process that yields the desired productssolid phase modification, shape, or size distributionsand by the robust analytical methods used for solid state characterization. This situation is greatly complicated by the recent emphasis on an exclusively * Corresponding author. Tel: 734-763-0101. Fax: 734-763-2022. e-mail: nrh@umich.edu. † University of Michigan. ‡ Dupont Pharmaceuticals. July 1999

The effects of the business model on object-oriented software development productivity

Unless the business model that governs software production adjusts to new technology, it is unlikely that an investment in the technology will result in real productivity benefits. Commercial development always takes place in the context of a business model, and in that context an understanding of how business constraints influence commercial software development is imperative. As software markets become more competitive and business pressures shorten software development cycles, improved software development productivity continues to be a major concern in the software industry. Many believe that new software technology, such as object-oriented development, provides a breakthrough solution to this problem. Unfortunately, there is little quantitative evidence for this belief. In this paper we explore the relationship between the business model and the productivity that a software development methodology can achieve in a commercial environment under that model. We first examine empirical data from several commercial products developed using object-oriented methods. The results indicate that object-oriented development may not perform any better than “procedural” development in environments that lack incentives for early completion of intermediate project tasks. We then model and simulate the impact of the software task-completion incentives and deadlines on the productivity that might be expected from a technology with high-performance potential. We show how and why some common business practices might lower project productivity and project completion probability. We also discuss to what extent poor software process control and (im)maturity of the technology compounds the problem.

Lessons from the Acceptance Tests on the CEC Photovoltaic Pilot Plants

Abstract Official acceptance tests, involving performance measurement, visual inspection and functioning checks, have been carried out on all fifteen of the photovoltaic pilot plants in the European Commission' second 4-year programme of solar energy R&D. Equipment and procedures developed for on-site performance measurement have been successfully applied throughout the year - even in an English November. All installations were found to be aesthetically pleasing, in accordance with CEC guidelines, but there is scope for reducing the costs of site preparation, support structures and array installation. Some of the modules were of high quality but others had low efficiency, poor process control and unsatisfactory arrangements for mounting and interconnection -faults which should be remedied in today's highly competitive market. Measurement discrepancies could be reduced if all manufacturers adhered strictly to the current European standard, CEC Specification 101, Issue 2. A single international standard for reference cell calibration should be an aim for the future. Varistors used for lightning protection should be carefully chosen to withstand the highest operational voltages over many years without the type of progressive degradation, which, as has been seen, may lead to catastrophic failure.