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Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Semiconducting photoresists hold great promise for scale‐up manufacturing of organic field‐effect transistors (OFETs) for integrated organic electronics. While photolithographic p‐type OFETs have achieved a considerable balance among patterning precision, electrical properties and process stability, it remains challenging for n‐type OFETs due to the inherent limited mobility and ambient instability. Herein, a n‐type semiconducting photoresist (SPr) is developed that is compatible with photolithography procedures. By utilizing the solvent‐driven force, a self‐encapsulated blend film with gradient semiconductor phase is prepared, where the underneath transistor active layer is protected by the upper cross‐linked network, avoiding solvent erosion and air doping. As such, a mobility up to 1.1 cm2 V−1 s−1 that is comparable with amorphous Si is achieved, with remained mobility by ≈90% after long‐term exposure to developer and stripper or atmospheric conditions. The sub‐micrometer patterning accuracy of SPr enables the fabrication of organic transistor arrays with a density of 9 × 105 units cm−1, which is comparable to other state‐of‐the‐art devices fabricated by the printing or photolithography, demonstrating immense potential in integrated organic electronics. [ABSTRACT FROM AUTHOR]

Anaerobic co-digestion (AcoD) of fish sludge (FS) with food waste (FW), and fruit and vegetable waste (FVW) for biogas and methane production was optimised in small-scale bioreactors, and batch and semi-continuous pilot-scale digesters, under mesophilic (37 ℃) conditions. An experimental mixture design was first applied to small-scale biomethane potential (BMP) tests, to determine the optimal mixture proportions of the AcoD of FS, FW, and FVW that maximise the specific methane yield (SMY in NmLCH4 gVS−1). The optimal mixture proportion was 67%FS:18%FW:19%FVW (w/w), producing 401 mLCH4 gVS−1, which was 8 times higher than the SMY when FS was mono-digested (48 mLCH4 gVS−1). The SMY achieved in batch pilot-scale digesters were 70–82% of methane yields obtained in BMP tests under the same operating conditions, with stable biogas production and no apparent inhibition during the batch run. Semi-continuous operation of the pilot-scale digester was undertaken with organic loading rates (OLRs) of 1, 2, and 3 g V S L - 1 d - 1 , provided intermittently. However, the digester did not achieve stable biogas production at all of the evaluated OLRs, due to the intermittent feeding and accumulation of volatile fatty acids (VFAs): Improved process stability was achieved at an OLR of 2 g V S L - 1 d - 1 , compared to OLRs of 1 and 3 g V S L - 1 d - 1 . Optimisation of the AcoD process resulted in attractive biomethane yields from FS with FW and FVW co-feeds, indicating that producing biogas from co-digestion of FS with relevant substrates is a valuable managing tool for FS, while simultaneously providing renewable energy. The work provides novel data that elucidated optimal proportions in which to combine FS, FW and FVW to obtain optimal biogas production, and provided important new information relevant for the scale up and continuous operation of an AD process for treating FS. [ABSTRACT FROM AUTHOR]

In this paper some issues relative to the gap between the traditional theory of control charts and real problems practitioners encounter are discussed. We consider both the general reasons for this discrepancy and different examples of misunderstandings. The trend to develop statistics as mathematical branch of science in the area of statistical process control has led to (i) ignoring many real complexities; (ii) creating many new types of charts that rarely help practitioners to improve their processes. We offer some practical advices, such as the introduction of two types of the assignable causes of variations (internal and external); the refusal from a traditional assumption that repetitive measurements are always normally distributed; the simple and practically convenient technique to calculate control chart limits for highly non-normal data. As the main direction for future efforts, we offer to start discussion about the implementation of Shewhart control charts into the program of school education.

Wire electrochemical micromachining has good technical advantages in the processing of metal material microdevices. However, because it is a special material containing insoluble solid particles, 40CrNiMoA exhibits poor processing stability, frequent ignition, and serious electrode wear. In this study, an attempt was made to promote mass transfer, reduce or even avoid abnormal discharge, and reduce electrode loss using solution ultrasonic assistance. The experimental results show the following. First, the thickness of the workpiece has a great influence on the process stability, and it is difficult to stably process 2-mm workpieces without ultrasonic assistance. Second, increasing the voltage to 32 V to increase the slit width causes stronger discharge to occur because of the increase of products and particles. Third, ultrasound assistance can improve the interelectrode flow field, promoting the smooth progress of the reaction and protecting the electrode. Fourth, the electrode rotation speed can be increased to enhance the medium exchange, but the electrode loss increases because of the decrease in electrolysis ability. Finally, a square spiral structure (with an overall length of 31 mm) was processed stably by optimizing the parameters. [ABSTRACT FROM AUTHOR]

Solvent-free extrusion emulsification (SFEE) is a recently developed process for producing submicron particles of high viscosity polymers using a twin-screw extruder without hazardous solvents. Its rate dependency on mixing for catastrophic phase inversion makes the process knowingly sensitive to a variety of variables, included the manner by which it is started up. This study examined how transient dynamics at the beginning affects steady-state operations by varying the time for the surfactant-containing feed stream to reach its setpoint rate into the process, to better understand the mechanism of SFEE. The results showed that the path taken to reaching the setpoint conditions (i.e. transition time) determined process stability and whether successful emulsification occurred, not the actual setpoint conditions chosen. Combining particle size and residence time measurements with prior studies' data related to the rate of reactions benefiting interfacial growth between the polymer/water phases and inline rheological findings, this unusual transient sensitivity was attributed to insufficient surface-active species present creating a persistent segregated regime of the flow field in the first half of the dispersion zone that exhibits an unstable phase morphology. Returning to the desired operating window was only possible once this segregated regime was purged from the process. The study offers a continuous processing perspective to this phenomenon previously observable in batch for high viscosity oil phase systems. [ABSTRACT FROM AUTHOR]

Underwater welding offers a wide range of applications in a variety of disciplines. The notion of underwater welding appeals to many in the naval construction industry since it effectively repairs colliding and damaged ships. This paper mainly focuses on the characteristics of underwater weldings, such as arc bubble behaviour, rapid cooling and underwater welded joints. The properties of bubble behaviour, its effect on process stability and process parameters that influence bubble generation are discussed. Rapid cooling is a crucial problem faced by Underwater Wet Welding (UWW). Reducing welding speed and employing induction heating techniques can control the cooling rate while welding. The influence of water flow on weld metal shows that cold cracking is directly connected to the worse mechanical characteristics of wet weld joints under various flow conditions. The mechanisms of porosity generation are investigated using slag formation, CO production, hydrogen diffusion, and short-circuiting. Weld metal porosity is reduced when the hydrogen level and CO formation are reduced. Finally, the recent developments and challenges faced in UWW and industrial applications are addressed. [ABSTRACT FROM AUTHOR]

This study investigates a novel approach in modeling the system limits of a braked, high-speed yarn-laying process with in situ impregnation. Special attention is paid to the investigation of the yarn spool overrun after the robot has come to a standstill. This phenomenon occurs at low yarn tensions in combination with high traversing speed and/or acceleration. The modeling of the yarn spool overrun is carried out using physical equations, taking into account the travel speed, acceleration of the robot, and braking force of the spool brake. Previous research has confirmed various operating points of the yarn-laying process, but a comprehensive and complete analysis of the system limits at different operating points and speeds up to 2 m/s is missing. The result of the study is a novel model that describes the system boundaries of the direct-yarn-placement. Furthermore, models for robot braking time, carbon spool diameter, and spool mass are developed. The proposed models have an R 2 > 0.9674. Regarding the system stability boundaries, the calculations reveal that, as acceleration rises, the minimum tension requirement also increases. The same trend is found for system velocity. At a = 12.5 %, a minimum tension of 16 N suffices, compared to 23 N and 32 N at a = 25 % and 50%, respectively. The impact on tension of quadrupling the speed outweighs that of acceleration, with tension increasing by factors of up to 22.5 and 2, respectively. [ABSTRACT FROM AUTHOR]

This work concerns the laser wire directed energy deposition (LW-DED) additive manufacturing process. The objectives were two-fold: (1) process mapping – demarcating the process states as a function of the processing parameters; and (2) process monitoring – detecting process anomalies (instabilities) using data acquired from an in-situ meltpool imaging sensor. The LW-DED process enables high-throughput, near-net shape manufacturing. Without rigorous parameter control, however, LW-DED often introduces defects due to stochastic process drifts. To enhance scalability and reliability, it is essential to understand how LW-DED parameters affect processing regimes, and detect deleterious process drifts. In this work, single-track experiments were conducted over 128 combinations of laser power, scanning velocity, and linear mass density. Four process states were observed via high-speed imaging and delineated as stable, dripping, stubbing, and incomplete melting regimes. Physically intuitive meltpool features were used to train simple machine learning models for classifying the process state into one of the four regimes. The approach was benchmarked against computationally intense, black-box deep machine learning models that directly use as-received meltpool images. Using only six intuitive meltpool morphology and intensity signatures, the approach classified the LW-DED process state with statistical fidelity approaching 90 % (F1-score) compared to F1-score 87 % for deep learning models.

To stay competitive in today's global market, manufacturers must ensure products released to consumers, meet international regulations and standards and this can only be done by putting in place sampling plans to guarantee the release of quality lots of products into the market. Hence, the objective of this paper is to design a variables sampling plan for the released of packed yam flour in view of international regulations on the net content of packaged goods. Probability plots, operating characteristic curves, the average outgoing quality (AOQ), average outgoing quality limit (AOQL) and average total inspection (ATI) were useful measures to evaluate the fitness of the sampling plan using the Minitab 2021 statistical software package. The packing process net weight, was found to be normally distributed with a p-value of 0.075 and a process standard deviation of 2.16. A comparative analysis on sample size, sampling plan measures, such as the AOQ, AOQL, and ATI and in view of best practice, were decisive in selecting a sampling plan with a sample size of 31 packs per lot as the most economic plan for lot sentencing. A practical demonstration on this sampling plan usage was also showcased. This sampling plan elevates and improves the net content of the packed product released into the market in view of international regulatory laws. [ABSTRACT FROM AUTHOR]

Underwater Shielded Metal Arc Welding (SMAW) is highly affected by the welding depth. The arc and molten metal in contact with the surrounding environment cause operational and metallurgical challenges regarding arc stability, metal transfer, gas formation, high-cooling rates, and diffusible hydrogen uptake. The hydrostatic pressure causes losses in consumable fusion efficiency, constricts the arc, increases the number of short-circuit events, and consequently decreases the welded joint’s process quality. In the present study, the novel approach of pulsed welding current is applied to wet shielded metal arc welding and is operational characteristics are evaluated in detail. Automated welding using an arc-voltage control system was used to obtain reproducible results. For the pulse conditions, two values of pulse current combinations, taking 140 A as the mean value, were set (ΔI of 40 A and 80 A). The same pulse and base duration were chosen, giving pulsing frequencies of 2.5 Hz and 25 Hz. The voltage and current signals were acquired and the short-circuit numbers and melting rates were calculated by processing the data stability factors. As a result, it was possible to weld with lower average welding currents through pulsed-current technology. This new approach can improve the stability of the wet SMAW process and contribute to obtaining better-quality welds without any changes for the underwater welder. [ABSTRACT FROM AUTHOR]

In this paper some issues relative to the gap between the traditional theory of control charts and real problems practitioners encounter are discussed. We consider both the general reasons for this discrepancy and different examples of misunderstandings. The trend to develop statistics as mathematical branch of science in the area of statistical process control has led to (i) ignoring many real complexities; (ii) creating many new types of charts that rarely help practitioners to improve their processes. We offer some practical advices, such as the introduction of two types of the assignable causes of variations (internal and external); the refusal from a traditional assumption that repetitive measurements are always normally distributed; the simple and practically convenient technique to calculate control chart limits for highly non-normal data. As the main direction for future efforts, we offer to start discussion about the implementation of Shewhart control charts into the program of school education. [ABSTRACT FROM AUTHOR]

To stay competitive in today’s global market, manufacturers must ensure products released to consumers, meet international regulations and standards and this can only be done by putting in place sampling plans to guarantee the release of quality lots of products into the market. Hence, the objective of this paper is to design a variables sampling plan for the released of packed yam flour in view of international regulations on the net content of packaged goods. Probability plots, operating characteristic curves, the average outgoing quality (AOQ), average outgoing quality limit (AOQL) and average total inspection (ATI) were useful measures to evaluate the fitness of the sampling plan using the Minitab 2021 statistical software package. The packing process net weight, was found to be normally distributed with a p-value of 0.075 and a process standard deviation of 2.16. A comparative analysis on sample size, sampling plan measures, such as the AOQ, AOQL, and ATI and in view of best practice, were decisive in selecting a sampling plan with a sample size of 31 packs per lot as the most economic plan for lot sentencing. A practical demonstration on this sampling plan usage was also showcased. This sampling plan elevates and improves the net content of the packed product released into the market in view of international regulatory laws.

Scientific relevance. The quality of medicinal products, particularly vaccines, is contingent on the stability of the manufacturing process at all stages, which can be evaluated using Shewhart charts for data obtained by monitoring the quality attributes of interest.Aim. This study evaluated the stability of the quality and manufacturing processes of the BCG and BCG-M tuberculosis vaccines using Shewhart charts.Materials and methods. This study focused on samples of the BCG tuberculosis vaccine and the BCG-M tuberculosis vaccine, a less reactogenic alternative for primary immunisation. Both vaccines were released to the market in 2019–2022. The quality of samples was assessed for stability based on their potency and total bacterial count, which are the key parameters for immunogenicity evaluation. These quality parameters were compared using test results submitted by the manufacturer and obtained at the testing centre. The authors plotted individuals charts (X-charts) and moving range charts (R-charts) in accordance with national standards GOST R 50779.42-99 and GOST R ISO 7870-2-2015.Results. The quality of the BCG and BCG-M vaccines remained stable during the entire follow-up period (2019–2022). For some periods, the retrospective analysis of R- and X-charts revealed characteristic trends meeting special cause criteria. The Pearson correlation coefficient (r) between the data submitted by the manufacturer and the data obtained at the testing centre ranged from 0.2 to 0.8.Conclusions. The Shewhart charts demonstrated that the quality parameters of the BCG and BCG-M tuberculosis vaccines tested in 2019–2022 were stable. These vaccines had stable manufacturing processes, as shown by the R- and X-charts. However, the warning signs indicated that additional measures should be taken to standardise the manufacturing processes. The findings suggest that Shewhart charts may be recommended for monitoring the production and quality of tuberculosis vaccines.

300 M ultra-high-strength steel (UHSS) is widely used to produce landing gear components for aircraft. The conventional manufacturing route for these components involves extensive machining and significant material wastage. Here, the application of wire-based gas metal arc additive manufacturing to produce 300 M UHSS parts was investigated. In particular, the influence of torch shielding atmosphere on the process stability and material performance of 300 M UHSS was investigated. The shielding gases used for comparison are pure Ar, Ar with 2.5% CO2, Ar with 8% CO2, Ar with 20% CO2, and Ar with 2% CO2 and 38% He. It was found that the arc length decreased, the transfer mode changed from spray to droplet mode, and spattering became more severe as the CO2 proportion increased. Additionally, replacing Ar with He led to a broader arc core, and a slightly shorter arc length and maintained a spray transfer, which decreased spatter. The wall surface roughness followed the trend in spatter, becoming worse with the increasing CO2 proportion, and better with He addition. Adding CO2 and He in pure Ar significantly increased the bead and wall width. The microstructure and mechanical properties exhibited a strong location dependence in the as-built state, with fresh martensite and higher strength in the top region, and tempered martensite and better ductility in the reheated bulk. Generally, torch shielding gas composition appeared to have no significant effect on the microstructure evolution. This study provides a reference for the subsequent application of gas metal arc additive manufacturing to aircraft landing gear mass production to achieve a high deposition rate and process stability simultaneously. [ABSTRACT FROM AUTHOR]

Anaerobic digestion is an established sustainable route for managing the organic fraction of municipal solid waste. The commonly adopted mono digestion of organic waste is often beset by many challenges chief of which is process instability. This study assessed the role of biochar in process stability and pathogen fate for batch co-digestion of food waste (FW) and cattle rumen content (CRC). Biochar had different functional groups, a large surface area (627.50 m2/g), and a pore volume (0.32 cm3/g). Biochar amendments helped stabilize the pH and reduce the accumulation of volatile fatty acids (VFAs) and total ammonia nitrogen (TAN). Biochar amendment using 5 g biochar also facilitated biogas production at low pH conditions (3.72 - 4.45), yielding a cumulative biogas yield of 706.11 ml/gVS with a biomethane composition of 64.3%. Pathogen counts revealed significant log reductions in the range 3.0-3.2 for E. coli, Bacillus, and Salmonella within the first 7 days of digestion, corresponding to 99.9% removal, indicating the safety of the resulting digestate for agricultural use. The modified Gompertz model adequately represented the kinetics of the anaerobic digestion process. The study has provided insights into biochar-facilitated digestion of CRC and FW for enhanced process stability. [ABSTRACT FROM AUTHOR]

Variation of the digester temperature during the year enables the operation of digesters as seasonal heat storage contributing to a holistic heat management at water resource recovery facilities. Full‐ and lab‐scale process data were conducted to examine the effect of the digester temperature on process stability, sludge liquor quality, and dewaterability. Both full‐ and lab‐scale digesters show a stable anaerobic degradation process with a hydraulic retention time of more than 20 days and organic load rates up to 2.2‐kg COD/(m3·day) at temperatures between 33 and 53°C. The concentrations of soluble COD and ammonium‐nitrogen in the sludge liquor digested at 53°C are 2.6 to 5.8 times and 1.3 times higher, respectively, than in the sludge liquor digested at 37°C. Dewatering tests show an enhancement of the dewaterability but a clear increase in the polymer demand at increased digester temperature. Practitioner Points: Digesters can operate as seasonal heat storage within mesophilic and thermophilic temperaturesStable anaerobic degradation process for HRT above 20 daysMaintenance of process stability as well as quantity and quality of biogasIncrease of soluble COD in sludge liquor at higher temperaturesBetter dewaterability but higher demand for polymers with increasing temperature [ABSTRACT FROM AUTHOR]

Digesters at water resource recovery facilities (WRRFs) operating at different temperatures within the mesophilic and thermophilic temperature range is a flexibilization concept to contribute to heat management. Four 25 L digesters were fed with sewage sludge from a municipal WRRF and were operated at 37, 43, 47 and 53 °C, respectively, to describe changes in the overall process performance and the microbiota. Specific methane yield and COD degradation rates were the highest at 47 °C, only being up to 7% higher compared with at 37 °C. The increase in pH and concentrations of NH4-N and PO4-P above 43 °C were statistically significant. The effect on the microbial community was strong, indicating both a constant specialization towards thermophilic organisms as well as a change from acetoclastic to hydrogenotrophic/methylotrophic methanogenesis. The influence of temperature on process-engineering and physicochemical aspects was rather small compared with the changes in the microbiota. [ABSTRACT FROM AUTHOR]

An extremely important issue in quality management is monitoring and diagnosing processes, and, subsequently, supervising them using so-called control charts. In typical production processes, charts with constant parameters are commonly used, such as x-R, x-s, CUSUM, EWMA and others, which, in most cases, are effective tools for process stability evaluation. Charts considered untypical (in statistical process control) are those with variable sample sizes, variable sampling intervals and/or variable control limits. Such charts are used when process analysis based on standard, well-known charts may lead to serious errors. Modern control charts are a response to the requirements of Industry 4.0 and are an excellent tool for supervising production processes. Their use together with Cp and Cpk indices and other process capability indices is a starting point for process improvement. The methodology of nonstandard charts is inadequately recognized and rarely used in practice. The theory of their design and examples of their use will be presented and characterized in this paper. [ABSTRACT FROM AUTHOR]

Steels with high carbon content can hardly or not at all be welded, but are of great interest for cladding applications due to their high hardness. In this study, the influence of process parameters on weld seam geometry and process stability is investigated when welding AISI 52100 bearing steel using the laser hot-wire cladding process. Process stability is evaluated using actual and set values for the wire feed rate and current parameters to determine a process window for a stable welding process. Weld seams are measured and analyzed in terms of width, height, contact angle, and shape. The effect of the process parameters on the weld seam geometry is investigated and appropriate mathematical functions to describe the geometry are determined. Process parameter sets in the range of 1-2 m/min wire feed rate and 45-75 A hot wire current were investigated. Unstable parameter sets occur clustered at high wire feed rate of 2 m/min for all hot wire currents. In addition, the process is unstable at high hot wire current of 75 A and low wire feed speed of 1 m/min. The remaining parameter sets resulted in a stable process. The investigated functions parabolic, cosinusoidal and circular arc for the mathematical description of the weld seam geometry, no clearly significant result could be determined. Only a trend towards the circular arc function and the parabolic function is apparent.

Anaerobic digestion is an established sustainable route for managing the organic fraction of municipal solid waste. The commonly adopted mono digestion of organic waste is often beset by many challenges chief of which is process instability. This study assessed the role of biochar in process stability and pathogen fate for batch co-digestion of food waste (FW) and cattle rumen content (CRC). Biochar had different functional groups, a large surface area (627.50 m2/g), and a pore volume (0.32 cm3/g). Biochar amendments helped stabilize the pH and reduce the accumulation of volatile fatty acids (VFAs) and total ammonia nitrogen (TAN). Biochar amendment using 5 g biochar also facilitated biogas production at low pH conditions (3.72 – 4.45), yielding a cumulative biogas yield of 706.11 ml/gVS with a biomethane composition of 64.3%. Pathogen counts revealed significant log reductions in the range 3.0–3.2 for E. coli, Bacillus, and Salmonella within the first 7 days of digestion, corresponding to 99.9% removal, indicating the safety of the resulting digestate for agricultural use. The modified Gompertz model adequately represented the kinetics of the anaerobic digestion process. The study has provided insights into biochar-facilitated digestion of CRC and FW for enhanced process stability.

This paper aims to develop an efficient debris-flushing technique for micro-EDM dressing to improve its process stability by providing a rotation to the dielectric medium. A setup was developed in-house in this regard to impart rotation to the dielectric medium at various speeds. To evaluate the efficiency of this flushing approach, the micro-EDM dressing process stability was assessed by monitoring and analyzing debris expulsion in real time with the aid of a high-speed photography and image processing technique on an immerging Ti6Al7Nb biomedical material. The process stability was appraised by monitoring and quantifying the (a) normal and arcing pulses % with the help of a developed pulse discriminating system and (b) the workpiece retraction captured in real time by a laser triangulation displacement sensor for the whole duration of machining. Additionally, the physics behind debris exclusions captured through high-speed photography under dielectric rotation was understood by analyzing the debris flow behavior in the discharge gap using a COMSOL Multiphysics model. The results show that the proposed flushing approach was capable to improve the micro-EDM dressing process stability significantly in comparison to no dielectric medium rotation case. The debris evacuation results were also found in good agreement with the process stability results. From the comparison, it was found that as high as ~17% more normal pulses with a reduction in spindle retraction height by more than 98% were achievable at the highest dielectric rotational speed in comparison to the no rotation condition. [ABSTRACT FROM AUTHOR]

Process forces are an integral characteristic for the evaluation of machining operations, which can be calculated using, for instance, empirical models. An adequate prediction is essential, especially as it provides input data for subsequent models, e.g., for stability analysis of milling processes. However, the calibration of force model coefficients is not unambiguous and may have multiple local optima, which can significantly affect the accuracy of the approximation of the cutting forces. In this context, the selection of experiments used for calibration is crucial to obtain adequate results. In this paper, a systematic analysis of the selection of the required calibration experiments and the influence of the resulting parametrization of the coefficients on the predicted milling forces and the stability limit was conducted.Based on the results, designs of calibration experiments could be identified, with which the influence of varying undeformed chip thicknesses could be represented adequately. By applying these force model parameterizations for stability analysis, an improvement in the prediction of stability limits was achieved. [ABSTRACT FROM AUTHOR]

Tunisia is one of the developing countries which faces crucial challenges, the most prominent of which are the production of organic waste, the need for an appropriate waste treatment, and the demand for water and energy conservation. To this end, the present research was designed to develop a technical concept on closed cycle "biowaste to bioenergy" treating food waste (FW) through combined biological processes. In this approach, semi-continuous anaerobic co-digestion (ACoD) of FW, wheat straw (WS), and cattle manure (CM) was tested to investigate the relationship between the effect of the feedstock mixtures and C:N ratio on biogas and digestate generation at different organic loading rates (OLRs) ranging from 2 to 3.6 kg VS/m3.d. Results showed that the mono-digested FW was optimal and reached 565.5 LN/kg VSin at an OLR of 2.4 kg VS/m3.d, and then a drop of biogas production was recorded. However, for co-digested substrates, the optimum mixture ratio was FW:CM 75:25, where 62%, 39.89%, 91.26%, 130.9%, and 119.97% of the biogas yield improved for OLRs ranging from 2 to 3.6 kg VS/m3.d, respectively. Admittedly, the target of this work was to enhance the ACoD process, but it also examined the exploitation of different AD effluents. Therefore, special attention was paid to the generated digestates to decide how it can be efficiently upcycled later. Thus, the closed cycle "biowaste to bioenergy" treatment met two of the major Tunisian concerns: efficient organic waste management and sustainable bioenergy production. [ABSTRACT FROM AUTHOR]

Copyright of Advances in New & Renewable Energy is the property of Editorial Office of Advances in New & Renewable Energy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There are many criticisms for the association between the Six Sigma concept and the two statistical metrics associated to 6σ processes: 1.5σ shift for maximum deviation and 3.4 PPM non-conformities for the long-term performance. As a result, the paper aims to carry out an analysis of this problem, and the first result obtained is that a stable process can reach a maximum drift, but its value depends on the volume of the sample. It is also highlighted that, using only the criterion "values outside the control limits" for monitoring stability through the Xbar chart, a minimum value can be calculated for the long-term performance of a process depending on the sample size. The main conclusion resulting from the calculations is that, in the case of a 6σ process, the long-term performance is much better than the established value of 3400 PPB: For small volume samples of two pieces it is below 700 PPB, for three pieces it is below 200 PPB, and for samples with a volume greater than or equal to four pieces the performance already reaches values below 100 PPB! So, the long-term performance of 6σ processes is certainly even better than the known value of 3.4 PPM. [ABSTRACT FROM AUTHOR]

The article presents the results of the strength properties of 12 ÷ 24 mm ribbed bars used for concrete reinforcement. The strength properties and the ribbing geometry of the ribbed bars is a key factor in ensuring the safety of building structures. Therefore, the continuous analysis of the mechanical parameters of ribbed bars and the reasons for their change is essential for any rolling mill. This article aims to present an analysis of the strength properties of ribbed bars made of high ductility steel in 2021 in a selected production plant, and then, based on the obtained results, to perform an analysis aimed at verifying the stability of the rolling process.

The study aimed to comprehensively determine P extraction efficiency and co-digestion of food waste (FW) and primary settled-nightsoil sludge (PSNS) process performance influenced by different hydraulic retention times (4, 7, 10, and 15 days) and mixture ratios of FW:PSNS in substrates (100:0, 75:25, 50:50, 25:75, and 0:100). P-transformation was evaluated to identify P fractionation in both supernatant and sludge accumulated in reactors. The results showed that anaerobic co-digestion was inhibited by the accumulation of undigested feedstock due to higher %PSNS found in AD4 (25FW:75PSNS) and AD5 (100PSNS). A more stable process was found in AD2 (75FW:25PSNS) under hydraulic retention time (HRT) 15 days in which COD removal efficiency and P release were 97.2 and 80.2%, respectively. This recommended condition allowed a high organic loading rate (OLR) at 12 gVS/L/day resulting in the highest biogas yield of 0.93 L/L/day. Distribution of P data demonstrated that most of P in feedstock was deposited and accumulated in sediment up to 97.8%. Poor biodegradability resulting from using shortened HRT led to high increased P-solid content in effluent. In addition, available P in effluents and accumulated P-solids in sediment obtained from the AcoD process has the potential to serve as sources for P recovery. [ABSTRACT FROM AUTHOR]

The use of stability lobe diagrams in milling is an established tool which is based on the compliance of the production system. Impact hammer tests can be performed to measure this compliance, usually at the tip of the non-rotating tool. In this contribution, a systematic characterization of the dynamic compliance is conducted considering the spindle speed-specific influence of a rotating tool on the modal parameters. To account for this, the resulting data was analyzed to allow for a spindle speed-dependent interpolation of these parameter values, which was used for the simulation-based prediction of stability lobe diagrams. [ABSTRACT FROM AUTHOR]

In this publication, the application of an implemented Digital Twin (DT) framework is presented by orchestration of CAM-integrated and containerized technology models carrying out FEM-coupled simulations for the finishing process of a simplified blade integrated disk (blisk) demonstrator. As a case study, the continuous acquisition, processing and usage of virtual process planning and simulation data as well as real machine and sensor data along the value chain is presented. The use case demonstrates the successful application of the underlying DT framework implementation for the prediction of the continuously changing dynamic behavior of the workpiece and according stable spindle speeds in the process planning phase as well as their validation in the actual manufacturing phase. [ABSTRACT FROM AUTHOR]

Slow hydrolysis persistently affects the anaerobic digestion of animal manure. Thermophilic and hyper-thermophilic treatments introduced into a two-stage anaerobic process treating pig manure were investigated, with a single-stage mesophilic process as a control. The results from the 100-day experiment showed the thermophilic-mesophilic system had the highest removal efficiency of volatile solids at 60.8%, 18% higher than the single-stage process. The thermophilic and hyper-thermophilic hydrolysis reactors contributed 23.5% and 21.7% solubilization of chemical oxygen demand (COD), respectively. The hydrolysis efficiency achieved in the single process was 49.7%, which was lower than the hydrolysis in the two-stage processes. Approximately 60% of COD was distributed in the solid fraction in the first stage, and more than half of the particle COD continued to hydrolyze in the subsequent second stage. The mass balance of COD and volatile solids removal performance illustrated the advantages of the temperature-phased process. Comparatively, the three mesophilic reactors all had strong stability. [ABSTRACT FROM AUTHOR]

In the past, few researchers have presented objective criteria that can be applied for the stability assessment of a gasification process for woody biomass. When exploring new operating points, however, an objective rating of the operation must be performed. Therefore, in this paper, a useful stability criterion by comparing different statistical parameters (i.e., standard deviation, relative standard deviation, interquartile range and stability index) for several gasifier variables (i.e., temperatures, pressure loss, air flow, permanent gases, total hydrocarbon content THC and flame front position) is described. Therefore, 124 operating points from different evaluations in a commercial open-top gasifier operated with wood chips were used. These data points include fuel water contents from 2 m% to 21 m%, exhaust gas recirculation, loads within the range of ±20% of the nominal load, water injection and air preheating. By taking this novel approach, three main findings were revealed: (1) The summarized standard deviation of the gasifier temperatures is suitable to rate the process stability; however, the temperature fluctuations showed no influence on the permanent gases. (2) A correlation was found between the standard deviation of the air flow and the absolute value of the THC ; this enables an estimation of the gas quality with a cheap air flow sensor. (3) A novel method was developed to identify stable operating timespans during post-processing based on the moving standard deviation. This procedure enables researchers to objectively rate operating points in future gasification development. • Evaluation of 124 different operating points in one gasifier setup. • Standard deviation of temperatures is suitable to rate the process stability. • Permanent gases CO, CO 2 , H 2 and CH 4 are not related to process stability. • Correlation was found between the standard deviation of the air flow and the THC. • Novel method for the selection of steady state timespans in post-processing. [ABSTRACT FROM AUTHOR]

The successful upscaling of anaerobic fermentation (AF) still relies on ensuring the stable production of volatile fatty acids (VFAs) in high concentrations and yields. The unforeseen events taking place at industrial scale can compromise the AF stability, thereby decreasing the cost-effectiveness of the process. To assess process stability against disturbances and identify AF failure indicators, this investigation explored the effect of starvation and pH control failure in a continuous reactor. The starvation disturbance did not affect AF performance and methanogenesis was not restored, confirming the relevance of selecting proper conditions (25 °C and pH 6.5) to ensure methanogenesis suppression. By contrast, the uncontrolled pH provoked a pH drop to 4.5, limiting the acidogenesis metabolisms and modifying the metabolites profile due to microbiome reshape. Lactobacillus , and members of Lactobacillaceae, Lactobacillales, and Bifidobacteriaceae dominated the microbiome in the pH disturbance, revealing lactic, succinic and oxalic acids as warning indicators of the acidogenesis failure. Nevertheless, the AF was completely recovered after the disturbances evidencing the microbiome robustness against pH range between 4.5 and 5. • 25 °C and pH 6.5 suppressed methanogenic activity at long hydraulic retention time. • Starvation period shorter than hydraulic retention time did not alter process yield. • pH drop limited acidogenesis while hydrolysis remained highly efficient. • Lactic, succinic and oxalic acids indicated the level of process damage. • Metabolic plasticity enabled microbiota recovery after disturbances. [ABSTRACT FROM AUTHOR]

[Display omitted] • Directed energy deposition meltpool data was collected from 128 unique process parameter combinations using in-situ, high-speed imaging. • Six physically intuitive meltpool features based in meltpool morphology and intensity were extracted from in-situ images. • Machine learning models were trained to classify meltpool features into one of four possible regimes: stable melting, stubbing, dripping, or incomplete melting. • Simple machine learning models achieved nearly 90% statistical fidelity, comparable to complex and computationally intense deep learning algorithms. This work concerns the laser wire directed energy deposition (LW-DED) additive manufacturing process. The objectives were two-fold: (1) process mapping – demarcating the process states as a function of the processing parameters; and (2) process monitoring – detecting process anomalies (instabilities) using data acquired from an in-situ meltpool imaging sensor. The LW-DED process enables high-throughput, near-net shape manufacturing. Without rigorous parameter control, however, LW-DED often introduces defects due to stochastic process drifts. To enhance scalability and reliability, it is essential to understand how LW-DED parameters affect processing regimes, and detect deleterious process drifts. In this work, single-track experiments were conducted over 128 combinations of laser power, scanning velocity, and linear mass density. Four process states were observed via high-speed imaging and delineated as stable, dripping, stubbing, and incomplete melting regimes. Physically intuitive meltpool features were used to train simple machine learning models for classifying the process state into one of the four regimes. The approach was benchmarked against computationally intense, black-box deep machine learning models that directly use as-received meltpool images. Using only six intuitive meltpool morphology and intensity signatures, the approach classified the LW-DED process state with statistical fidelity approaching 90 % (F1-score) compared to F1-score 87 % for deep learning models. [ABSTRACT FROM AUTHOR]

The research paper was prepared within the framework of a project whose aim is to improve the durability of the corrosion protection properties of the product by regulating the input parameters of the cross-wire welding process. Cross-wire welding is a subtype of electric resistance welding. Products made by the cross-wire welding process are widely used in everyday life and can be found in the form of grids, gratings, fencing systems, baskets, guards, etc. The subject of the research work is a preliminary analysis of the stability of the cross-wire welding process. The results of the performed analysis will serve as a starting point for the second phase of the project. Since the recorded values of the set down output parameter differ significantly from the expected values, this parameter is considered as an indicator of the process stability. From the specific trend of the results in the performed analysis, it was concluded that the position of the electrode has a significant influence on the result, which was confirmed by comparing the test results before and after the preliminary tests.

In this publication, the application of an implemented Digital Twin (DT) framework is presented by orchestration of CAM-integrated and containerized technology models carrying out FEM-coupled simulations for the finishing process of a simplified blade integrated disk (blisk) demonstrator. As a case study, the continuous acquisition, processing and usage of virtual process planning and simulation data as well as real machine and sensor data along the value chain is presented. The use case demonstrates the successful application of the underlying DT framework implementation for the prediction of the continuously changing dynamic behavior of the workpiece and according stable spindle speeds in the process planning phase as well as their validation in the actual manufacturing phase.

In this work, the types of metallic transfer present in electric arc welding with tubular wire and the main characteristics of the pulsed current technique applied in underwater wet welding are exposed. For this, it was essential to collect and analyze the information from different investigations, condensed into technical-scientific articles. This document is divided into two sections: first, the effect that the parameters and conditions of the process have on the type of metal transfer is elucidated. In addition, the application of the pulsed current is presented, and its effect on the control of the size of the metal drops, as well as its frequency and mode of detachment from the electrode to the weld pool. [ABSTRACT FROM AUTHOR]

Cross-feeding based on amino acids metabolism is an important strategy by which anammox bacteria and the co-existing heterotrophs facilitate their own growth and survival. Arginine is one of the necessary amino acids required for bacterial protein biosynthesis but whether adding arginine could benefit growth of anammox bacteria remains unknown. In this study, arginine was supplemented at dose of 5 mg·L -1 to promote the nitrogen removal performance of anammox bioreactors under varied loading rates. The results showed that nitrogen removal efficiency increased by 10.2 % under higher loading rates. Arginine addition substantially simulated the secretion of extracellular proteins and polysaccharides within anammox consortia as a strategy against unfavorable conditions. Canditatus Kuenenia dominated the anammox consortia and their 16S rRNA abundance and anammox-related functional genes were significantly increased by up to 0.42 times and 5.81 times, respectively. The findings of this study provided a feasible strategy to improve the performance of anammox reactors with arginine supplementation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Digesters at water resource recovery facilities (WRRFs) operating at different temperatures within the mesophilic and thermophilic temperature range is a flexibilization concept to contribute to heat management. Four 25 L digesters were fed with sewage sludge from a municipal WRRF and were operated at 37, 43, 47 and 53 °C, respectively, to describe changes in the overall process performance and the microbiota. Specific methane yield and COD degradation rates were the highest at 47 °C, only being up to 7% higher compared with at 37 °C. The increase in pH and concentrations of NH4-N and PO4-P above 43 °C were statistically significant. The effect on the microbial community was strong, indicating both a constant specialization towards thermophilic organisms as well as a change from acetoclastic to hydrogenotrophic/methylotrophic methanogenesis. The influence of temperature on process-engineering and physicochemical aspects was rather small compared with the changes in the microbiota.

Liquid column was a common problem in ultra-high power fiber laser-arc hybrid welding (UHLAHW) process, which has an adverse effect on the welding stability and weld formation. Hence, the influence of welding parameters on the behavior of liquid column was investigated systematically, including laser arc recombination process, laser power, and welding speed. As a result, the violent rising liquid column under laser was suppressed markedly after arc addition. However, it was hard to restrain liquid column upturn when laser power was extremely high, because the huge recoil pressure and shear force between metal vapor/plasma and molten pool could increase the upward momentum of melt. Besides, the height of liquid column and volume of spatters were directly influenced by welding speed, due to the welding line energy could significantly influence the flow of melt on the front of keyhole. By optimizing the welding process, the liquid column could be controlled, thereby significantly improving the welding process stability. Finally, a sound weld bead with qualified weld formation and 15.82-mm penetration was produced when the laser power was 21 kW and welding speed was 1.2 m/min under UHLAHW process. This work provides technical guidance for achieving stable welding process and qualified weld formation for thick plates. [ABSTRACT FROM AUTHOR]

Laser polishing (LP) is an advanced finishing technology used to improve surface quality through laser remelting of the surface topography. A thorough understanding of the surface topography formation during laser remelting is critically required to monitor, optimize, and control the LP process. For this purpose, a method for automated detection of laser-material interaction contour along a laser track was developed and was used to estimate the stable and unstable conditions of the LP process. Process instabilities can yield to significant variations of the longitudinal surface profiles and the remelted track width along the laser path. The proposed method relies on a first derivative-based determination of the two spatial contour boundaries that delimit the width of the remelted laser track. The developed technique was tested and applied to two experimentally obtained laser tracks under non-stable and stable LP process conditions. This study demonstrates the efficient applicability of the automated contour detection in advanced analysis, monitoring, optimization, and control of the LP process stability. [ABSTRACT FROM AUTHOR]

Surface polishing by laser remelting (SP-LRM) uses the energy of a focused laser beam to remelt the thin top layer of the workpiece material in order to improve its surface quality by 3D topography smoothing. Visual observations of the experimentally-obtained remelted laser tracks revealed that the uniformity of the LRM surface topography highly depends on the stability of the laser-material interactions and initial surface topography. Two metrics of LRM topography were proposed to assess the LRM process stability: uniformity of the laser track contour and uniformity of the middle longitudinal profile. Several sub-areas of the LRM tracks with typical topographic nonuniformities were visually selected and their nonuniformity metrics determined. Two common types of surface topography nonuniformities characterized by distinctive geometric patterns were identified: those induced by the LRM process (excessively remelted material) and those affected by the surrounding initial surface topography. The obtained results open new research avenues toward the in-process estimation of the surface topography formation and evolution via online monitoring of the LRM process stability. [ABSTRACT FROM AUTHOR]

A twin-electrode TIG-MIG (T-TIG-MIG) indirect arc welding method was proposed in this paper. The arc behavior and droplet transfer process were preliminarily investigated; moreover, the process stability was assessed, and bead-on-plate welding was conducted. Results showed T-TIG-MIG indirect arc burnt between a wire and two tungsten electrodes and was essentially formed by the coupling of two single-electrode TIG-MIG indirect arcs. The wire feeding speed (WFS) determined the equilibrium position of the wire end, and the vicinity of the tungsten tips was an ideal position for arc shape and droplet detachment, where the arc was more concentrated with a higher coupling degree. With the increase of the welding current, the arc length and stiffness increased gradually; so did the process stability and the spreadability of the weld bead. When the current exceeded the critical current, the droplet transfer mode changed into streaming spray transfer, since the electromagnetic force and the arc pressure increased considerably. Compared to conventional cold-wire T-TIG welding under the same current, the wire deposition rate of T-TIG-MIG indirect arc welding increased by about 186%, while the range of the heat-affected zone reduced by about 41%. [ABSTRACT FROM AUTHOR]