Quality Monitoring Techniques Research Articles

Large-scale quantification of CVD graphene surface coverage

The extraordinary properties demonstrated for graphene and graphene-related materials can be fully exploited when a large-scale fabrication procedure is made available. Chemical vapor deposition (CVD) of graphene on Cu and Ni substrates is one of the most promising procedures to synthesize large-area and good quality graphene films. Parallel to the fabrication process, a large-scale quality monitoring technique is equally crucial. We demonstrate here a rapid and simple methodology that is able to probe the effectiveness of the growth process over a large substrate area for both Ni and Cu substrates. This method is based on inherent electrochemical signals generated by the underlying metal catalysts when fractures or discontinuities of the graphene film are present. The method can be applied immediately after the CVD growth process without the need for any graphene transfer step and represents a powerful quality monitoring technique for the assessment of large-scale fabrication of graphene by the CVD process.

Chemical and microbiological soil quality indicators and their potential to differentiate fertilization regimes in temperate agroecosystems

The study examined the interrelationships between chemical and microbiological quality indicators of soil and their ability to differentiate plots under contrasting fertilization regimes. The study was based on a long-term field experiment established on an Udic Ustocrepts in 1966. The soil was cropped with maize (Zea mays L.) and winter wheat (Triticum aestivum L.) and received no organic fertilization (control), wheat straw and maize stalk (crop residue) or cattle manure (manure) in combination with increasing levels of mineral N (N0 and N200). To asses whether seasonal fluctuations of measured properties might mask the effects of fertilization, soil samples were collected four times within a growing season. Manure amendment increased soil TOC and TN, while crop residue amendment had no significant effects. Mineral N increased TN only in April, while in September it decreased water extractable organic C (WEOC). Data of diffuse reflectance Fourier transform mid-infrared spectroscopy (DRIFTS) gave evidence for a higher relative contribution of the aliphatic peak at 2930cm−1 and a lower relative contribution of the aromatic peaks at 1620cm−1 and 1520cm−1 under manure. Manure amendment stimulated enzymatic activities, increased microbial biomass carbon (Cmic) and total phospholipids (PLFAs), and reduced the metabolic quotient (qCO2). Patterns of PLFAs indicated that manure amendment increased the ratio of Gram-positive to Gram-negative bacteria. Crop residue amendment had no significant effects, while in September mineral N inhibited protease activity and reduced the Gram-positive to Gram-negative ratio. Microbial-related parameters fluctuated over time but their seasonality did not hamper the identification of fertilization-induced effects. The selected properties proved to be valuable indicators of long-term changes of soil quality and were strongly interrelated: changes in soil organic matter content and composition induced by manure amendment were accompanied by changes in abundance and function of the soil microbial community. Partial least square analysis obtained relating DRIFTS spectra to measured soil properties produced accurate predictive models for TOC and PLFAs, and moderately accurate models for Cmic, showing the potential of DRIFTS to be used as a rapid soil testing technique for soil quality monitoring.

Measurement and Analysis of Electric Power Quality for Commercial Vessels

Owing to more and more sensitive loads installed in modern ships, ship owners and builders have been faced with rising numbers of complaints about the quality of power. However, the existing power monitoring facilities installed onboard for recording deviations of power parameters is only over steady-state conditions due to limited capacity of measurement equipment and ignores short-duration phenomena. To understand the true supply quality in ships, a power quality (PQ) monitoring technique is employed in this paper. The PQ parameters including short-duration and long-duration voltage and frequency variations in a practical commercial vessel power system under different operating conditions are analyzed and their statistic data are reported. Through PQ measurement and analysis, the quality of supply can be quantified and assessed according to classification society standards. Analysis model developed in this paper can assist them in understanding true supply quality in ships for further determining proper PQ mitigation options.

Low-Cost Oil Quality Sensor Based on Changes in Complex Permittivity

Real time oil quality monitoring techniques help to protect important industry assets, minimize downtime and reduce maintenance costs. The measurement of a lubricant’s complex permittivity is an effective indicator of the oil degradation process and it can be useful in condition based maintenance (CBM) to select the most adequate oil replacement maintenance schedules. A discussion of the working principles of an oil quality sensor based on a marginal oscillator to monitor the losses of the dielectric at high frequencies (>1 MHz) is presented. An electronic design procedure is covered which results in a low cost, effective and ruggedized sensor implementation suitable for use in harsh environments.

Prediction of traffic-related nitrogen oxides concentrations using Structural Time-Series models

Ambient air quality monitoring, modeling and compliance to the standards set by European Union (EU) directives and World Health Organization (WHO) guidelines are required to ensure the protection of human and environmental health. Congested urban areas are most susceptible to traffic-related air pollution which is the most problematic source of air pollution in Ireland. Long-term continuous real-time monitoring of ambient air quality at such urban centers is essential but often not realistic due to financial and operational constraints. Hence, the development of a resource-conservative ambient air quality monitoring technique is essential to ensure compliance with the threshold values set by the standards. As an intelligent and advanced statistical methodology, a Structural Time Series (STS) based approach has been introduced in this paper to develop a parsimonious and computationally simple air quality model. In STS methodology, the different components of a time-series dataset such as the trend, seasonal, cyclical and calendar variations can be modeled separately. To test the effectiveness of the proposed modeling strategy, average hourly concentrations of nitrogen dioxide and nitrogen oxides from a congested urban arterial in Dublin city center were modeled using STS methodology. The prediction error estimates from the developed air quality model indicate that the STS model can be a useful tool in predicting nitrogen dioxide and nitrogen oxides concentrations in urban areas and will be particularly useful in situations where the information on external variables such as meteorology or traffic volume is not available.

Agro-food farmland Environmental Monitoring Techniques and Equipment

In recent years, caused by farmland environment for agro-food safety events and sudden public events are gradually increase the situation. The current China agro-food environmental situation is far from optimistic. In this paper, new, fast and efficient farmland environment technology and instrument equipment already become this field of important scientific and technological requirements. Based on the comprehensive literatures, and on the basis of research achievements, combinative oneself from fast detection techniques of pesticide residues, heavy metal pollution fast detection techniques, and agro-food quality fast detection techniques, space monitoring technology, farmland environmental monitoring agricultural informatization. This paper expounds the agricultural aspects involved farmland environmental monitoring the related technologies and equipment, summarizes the China agro-food farmland environmental monitoring technology and equipment, and puts forward the advantage and shortage on computer technology as the foundation's future agro-food farmland environmental quality monitoring techniques and equipment information development new direction

An appraisal of a biocontamination assessment method for freshwater macroinvertebrate assemblages; a practical way to measure a significant biological pressure?

Freshwater invasive or alien species (IAS) can have a major impact on benthic macroinvertebrate assemblage structure and diversity. This has implications for accurate biological monitoring, the assessment of the ecological quality status of rivers and achievement of Water Framework Directive (WFD) objectives. Although IAS constitutes a major biological pressure to WFD objectives, current approaches to ecological status assessment tend to ignore their presence. This problem is compounded as biotic indices such as the Biological Monitoring Working Party (BMWP) score do not distinguish between native and IAS, when IAS tend to be more tolerant of organic pollution than the natives they replace. Biocontamination is the presence of an IAS in a system, and we tested a new method of biocontamination assessment, designed to be used alongside current routine water quality monitoring techniques, by applying it to biological monitoring data from the river monitoring programme of a small Island, The Isle of Man. Although 54% of monitoring sites exhibited no biocontamination, 19% showed low or moderate biocontamination and 27% high or severe biocontamination. Richness contamination was low (only two contaminated families being recorded), but abundance contamination was high in some sites (87% of individuals being IAS). Sites with a greater relative abundance of IAS individuals exhibited lower BMWP water quality. Within invaded sites BMWP monitoring was not responsive to changing chemical water quality, whereas within uninvaded sites it was. In invaded sites, the relative abundance of IAS increased as ammonia and BOD5 increased. Our study shows current monitoring approaches mask the presence of AIS within assemblages, with some highly biocontaminated sites registering high BMWP biological quality. This new index represents a simple way to integrate the IAS biological pressure into established WFD monitoring programmes, to produce more comprehensive estimates of ecological quality status than are currently being realised.

Faecal pollution source identification in an urbanising catchment using antibiotic resistance profiling, discriminant analysis and partial least squares regression

Increasing urbanisation and changes in land use lead to adverse impacts on the quality of natural water resources. The specific sources of contamination are often difficult to identify using conventional water quality monitoring techniques. This acts as a significant constraint to the development of appropriate management techniques to protect natural water resources. Consequently, alternative means of identifying pollutant sources and their locality are necessary. In this study, Antibiotic Resistance Patterns (ARP) were established for a library of 1005 known Escherichia coli source isolates obtained from human and non-human (domesticated animals, livestock and wild) sources in an urbanising catchment in Queensland State, Australia. Discriminant Analysis (DA) was used to differentiate between the ARP of source isolates and to identify the sources of faecal contamination. Partial Least Square (PLS) regression was then utilised on identified human source isolates to correlate their locality with specified sampling locations within the catchment. The resulting ARP DA indicated that a majority of the faecal contamination in the rural areas was non-human. However, the percentage of human isolates increased significantly in urbanised areas using onsite systems for wastewater treatment. The PLS regression was able to develop predictive models which indicated a high correlation of human source isolates from the urban area. The study results confirm the feasibility of using ARP for source tracking faecal contamination in surface waters, as well as predicting their point of origin.

Nitrogen sources and exports in an agricultural watershed in Southeast China

The nitrogen (N) budget was developed for Jiulong River Watershed (JRW), an agricultural watershed in a warm and humid area of southeast China. Water quality monitoring, field surveys, modelling and GIS techniques were applied to estimate N flux of atmospheric deposition, mineralization, runoff, denitrification, and ammonia volatilization. Over the whole watershed, fertilizers, import of animal feeds, biotic fixation, mineralization and atmospheric deposition contributed 67.1%, 16.5%, 2.1%, 4.9% and 9.5%, respectively, of total N input (129.3 kg N ha−1 year−1). Runoff, sale of production, denitrification, and ammonia volatilization contributed 7.3%, 24.4%, 10.5% and 57.8% of total N output (72.9 kg N ha−1 year−1), respectively. The N budget for the JRW suggested that more than 50% of the N input was lost to the environment, and about 14% was discharged as riverine N, which indicated that agricultural and human activities in the watershed substantially impacted the estuary and coastal water quality, and so altered the N biogeochemistry process.

Noncontact Photo-Acoustic Defect Detection in Drug Tablets

Quality assurance monitoring is of great importance in the pharmaceutical industry for the reason that if defects such as coating layer irregularities, internal cracks, and delamination are present in a drug tablet, the desired dose delivery and bioavailability can be compromised. The U.S. Food and Drug Administration (FDA) established the Process Analytical Technology (PAT) initiative, in order to ensure efficient quality monitoring at each stage of the manufacturing process by the integration of analysis systems into the evaluation procedure. Improving consistency and predictability of tablet action by improving quality and uniformity of tablet coatings as well as ensuring core integrity is required. An ideal technique for quality monitoring would be noninvasive, nondestructive, have a short measurement time, intrinsically safe, and relatively inexpensive. In the proposed acoustic system, a pulsed laser is utilized to generate noncontact mechanical excitations and interferometric detection of transient vibrations of the drug tablets is employed for sensing. Two novel methods to excite vibrational modes in drug tablets are developed and employed: (i) a vibration plate excited by a pulsed-laser and (ii) pulsed laser-induced plasma generated shockwave expansion. Damage in coat and/or core of a tablet weakens its mechanical stiffness and, consequently, affects its acoustic response to an external dynamic force field. From the analysis of frequency spectra and the time-frequency spectrograms obtained under both mechanisms, it can be concluded that defective tablets can be effectively differentiated from the defect-free ones and the proposed proof-of-concept techniques have potential to provide a technology platform to be used in the greater PAT effort.

In-service signal quality monitoring and multi-impairment discrimination based on asynchronous amplitude histogram evaluation for NRZ-DPSK systems

A novel in-service signal quality monitoring technique for nonreturn-to-zero differential phase-shift keying signals using asynchronous amplitude histogram evaluation has been demonstrated. As a result of phase-to-amplitude modulation, there are three Gaussian distributions in the amplitude histogram. The widths of the Gaussian distributions are related to the amount of amplified spontaneous emission, while the separations between the Gaussian distributions increase monotonically with fiber dispersion. The amount of dispersion and optical signal-to-noise ratio can, thus, be directly extracted and discriminated from the amplitude histogram.

環境しゅんせつ工法の汚濁発生調査事例と水質モニタリング手法の提案

During dredging of contaminated sediment as an environmental countermeasure, it is important to prevent secondary environmental pollution caused by turbidity generation. Especially, protection against dioxin diffusion should require controlof suspended solids (SS). In this paper, “ environmental dreading method ” and “real-time waterquality monitoring system ” we have developed were reported, that have been found suitable to practical application. As the result of on-site investigation, actual measurements of turbidity during the“environmental dreading method”demonstrated that it could effectively reduce turbidity compared to previously established methods. In addition, a new real-time water quality (SS) monitoring technique and a framework of its operation combined with an environmental dredging were proposed.

Development of a concept for integrated ecological river assessment in Flanders, Belgium

Integrated river management is based on monitoring, modelling and assessment of the water cycle. Effective and efficient management is only possible when these three activities are well interconnected and concerted. The choice of appropriate, high quality monitoring techniques is probably one of the most crucial factors in the assessment of river systems. To this end, the EU has recently adopted a Water Framework Directive. Although this Directive provides the guidelines for monitoring water bodies, local governments still have a lot of freedom regarding their practical implementation. The development of a consistent monitoring and assessment strategy and methodology is therefore essential for each European country. This paper discusses different Flemish techniques for the monitoring and assessment of macro-invertebrates and fish communities in relation to water quantity and the physical, chemical, morphological and structural quality. Finally, a concept for sustainable and integrated ecological assessment and management is presented.

On all-optical laser cleaning and inspection of contaminated concave metal surfaces

A technique for all-optical laser cleaning and surface quality monitoring of concave metal surfaces is suggested. Contaminated pharmaceutical punches from a tablet compression machine were cleaned using high-energy laser pulses. Image information obtained from a diffractive-optical-element-based sensor was used in inspection of the surface quality change of the concave punches due to laser cleaning. Alternative method for mechanical cleaning of punches is introduced, which is based on simultaneous laser cleaning and surface quality inspection of the punches.

Ultrasonic wire-bond quality monitoring using piezoelectric sensor

This paper describes an ultrasonic wire-bond quality monitoring technique which involves the detection of changes in the mechanical impedance of the bond zone during bond formation by monitoring the changes in the ultrasonic vibrations of an ultrasonic wire-bonding transducer system. A lead zirconate titanate (PZT) piezoelectric ceramic having properties similar to the commercial PZT-5A has been selected as the sensor material. A PZT piezoelectric sensor is installed on an appropriate location on the transducer in order to measure the ultrasonic amplitude and bonding time during the bonding process. This sensor has dimensions 1 mm × 1 mm × 0.245 mm to avoid excessive loading on the transducer and to obtain a flat frequency response. A bond quality monitoring system has been developed to process and record the non-linear signal detected by the sensor. More significant changes are observed at the higher-frequency harmonics (second harmonic) of the ultrasonic signal. Good correlation is found between the change in the second harmonic and the bond quality. Bonding process drift towards unacceptable bond quality can be identified. This technique will be used to develop a multiparameter-based automatic process-control system for wire bonding.

Online pattern‐based part quality monitoring of the injection molding process

AbstractThe quality of injection molded parts is currently monitored in the plant using techniques that focus on the statistical analysis of discrete data and, in particular, peak values. This paper presents an alternative online technique for part quality monitoring that focuses on the analysis of complete data patterns. Specifically, this paper discusses the application of artificial neural networks (ANNs) as part quality monitoring tools. The method of approach is to train a back propagation network (BPN) to associate part quality with the corresponding data pattern produced during injection. In Part I of this work, the data pattern consists of a series of discrete values and the part quality measure is defined as part weight. In Part II, the data pattern is the measurement profile observed from a pressure sensor placed in the mold cavity and the part quality measure is defined as part length. Results show that ANNs are successful in predicting part quality based on data patterns when an entire sensor profile is analyzed. Furthermore, demonstrations show that the approach is superior in predicting part quality when compared to statistical techniques now widely practiced by the injection molding process industry.

A technique for groundwater quality monitoring using resistivity measurements made through a modified plastic well-screen

Abstract A composite well-screen has been developed for resistivity measurements using high permeability ‘terran’ fabric wrapped around plastic well-screen containing 1.5 mm slots. Laboratory and in situ tests indicate that this screen presents a relatively small impedance to the flow of water and electricity while excluding fines that may be present. Experiments with the well-screen were made in situ after emplacement in an unconsolidated, dense, fine coastal sand body. Results are presented of electrical resistivity measurements made through the well-screen, using a focussed resistivity tool, which indicate that changes in groundwater conductivity could be monitored as changes in formation resistivity. The groundwater inside the well-screen has been logged but suffers from the possibility of vertical mixing whereas measurements through the casing do not. The well-screen also offers the possibility of taking water samples in unconsolidated sediments using a simple, very low pressure, double packer system. The effect of the well-screen on the resistivity measurements was found to be small after comparison with a self-bored resistivity log where the sand has been in direct contact with the formation.

Air quality impact assessment

Air quality impact assessment (AQIA) is an important technique for determining the relative contribution to ground level pollutant concentrations of specific current or future source emissions at receptor sites. The principal activities in AQIA are air quality modelling and monitoring techniques. The choice of techniques which are applicable to a particular situation is intimately related to the problem to be assessed. A review of relevant modelling techniques has been presented, with emphasis placed on Gaussian plume models because of their ease of use and broad applicability. Alternative modelling techniques have been suggested when departures from the Gaussian form in the atmosphere occurs or when more detailed information on atmospheric chemistry, deposition or long range transport is required. The objectives and techniques of ambient air quality monitoring have been examined and the siting of instruments, duration and frequency of sampling, choice of monitoring rationale (fixed or mobile), minimization of sampling errors, data storage and analysis are discussed. Modelling and monitoring are essential to successful AQIA. An orderly approach to the principles and procedures involved in performing AQIA studies, using these two techniques in conjunction, has been presented.

Water Purification by Forced-Flow Electrophoresis

The capabilities of an electrophoretic apparatus for water treatment are reported. Forced-flow electrophoresis—a modification of electrodecantation by Bier—provides two potential areas of application: (1) The concentration of micro-organisms or dilute solutions of organic compounds for the purposes of both identification and quantitative analysis, and (2) the removal of colloids and supra-colloids from surface waters. Concentration of dilute samples of bacteriophage T1 and 2, 4-D insecticide demonstrate a possible development as a water quality monitoring technique. Waters of low conductivity containing colloidal material can also be treated directly by electrophoresis for colloid separation. Scale-up beyond laboratory size models is dependent on reducing effects of scale and slime formation, spacer thickness, and sedimentation and clogging; as well as a need for better electrical power efficiency.