Abstract: The forensic use of handwriting depends on the analysis, comparison, and evaluation decisions made by forensic document examiners. When using biometric technology in forensic applications, it is necessary to compute Likelihood Ratio (LR) for quantifying strength of evidence under two competing hypotheses, namely the prosecution and the defense hypotheses wherein a set of assumptions and methods for a given data set will be made. It is therefore important to know how repeatable and reproducible our estimated LR is. This paper evaluated the accuracy and reproducibility of examiners' decisions. Confidence interval for the estimated LR were presented so as not get an incorrect estimate that will be used to deliver wrong judgment in the court of Law. The estimate of LR is fundamentally a Bayesian concept and we used two LR estimators, namely Logistic Regression (LoR) and Kernel Density Estimator (KDE) for this paper. The repeatability evaluation was carried out by retesting the initial experiment after an interval of six months to observe whether examiners would repeat their decisions for the estimated LR. The experimental results, which are based on handwriting dataset, show that LR has different confidence intervals which therefore implies that LR cannot be estimated with the same certainty everywhere. Though the LoR performed better than the KDE when tested using the same dataset, the two LR estimators investigated showed a consistent region in which LR value can be estimated confidently. These two findings advance our understanding of LR when used in computing the strength of evidence in handwriting using forensics.
Abstract: Biosensors play a significant role in the healthcare
sectors, scientific and technological progress. Developing electrodes
that are easy to manufacture and deliver better electrochemical
performance is advantageous for diagnostics and biosensing. They
can be implemented extensively in various analytical tasks such as
drug discovery, food safety, medical diagnostics, process controls,
security and defence, in addition to environmental monitoring.
Development of biosensors aims to create high-performance
electrochemical electrodes for diagnostics and biosensing. A
biosensor is a device that inspects the biological and chemical
reactions generated by the biological sample. A biosensor carries
out biological detection via a linked transducer and transmits the
biological response into an electrical signal; stability, selectivity,
and sensitivity are the dynamic and static characteristics that affect
and dictate the quality and performance of biosensors. In this
research, a developed experimental study for laser scribing technique
for graphene oxide inside a vacuum chamber for processing of
graphene oxide is presented. The processing of graphene oxide (GO)
was achieved using the laser scribing technique. The effect of the
laser scribing on the reduction of GO was investigated under two
conditions: atmosphere and vacuum. GO solvent was coated onto a
LightScribe DVD. The laser scribing technique was applied to reduce
GO layers to generate rGO. The micro-details for the morphological
structures of rGO and GO were visualised using scanning electron
microscopy (SEM) and Raman spectroscopy so that they could
be examined. The first electrode was a traditional graphene-based
electrode model, made under normal atmospheric conditions, whereas
the second model was a developed graphene electrode fabricated
under a vacuum state using a vacuum chamber. The purpose was
to control the vacuum conditions, such as the air pressure and the
temperature during the fabrication process. The parameters to be
assessed include the layer thickness and the continuous environment.
Results presented show high accuracy and repeatability achieving low
cost productivity.
Abstract: In this paper, we report the development of a portable and inexpensive infrared lightbox for improving the detection limits of paper-based phosphate devices. Commercial paper-based devices utilize the molybdenum blue protocol to detect phosphate in the environment. Although these devices are easy to use and have a long shelf life, their main deficiency is their low sensitivity based on the qualitative results obtained via a color chart. To improve the results, we constructed a compact infrared lightbox that communicates wirelessly with a smartphone. The system measures the absorbance of radiation for the molybdenum blue reaction in the infrared region of the spectrum. It consists of a lightbox illuminated by four infrared light-emitting diodes, an infrared digital camera, a Raspberry Pi microcontroller, a mini-router, and an iPhone to control the microcontroller. An iPhone application was also developed to analyze images captured by the infrared camera in order to quantify phosphate concentrations. Additionally, the app connects to an online data center to present a highly scalable worldwide system for tracking and analyzing field measurements. In this study, the detection limits for two popular commercial devices were improved by a factor of 4 for the Quantofix devices (from 1.3 ppm using visible light to 300 ppb using infrared illumination) and a factor of 6 for the Indigo units (from 9.2 ppm to 1.4 ppm) with repeatability of less than or equal to 1.2% relative standard deviation (RSD). The system also provides more granular concentration information compared to the discrete color chart used by commercial devices and it can be easily adapted for use in other applications.
Abstract: The thermal conductivity of thermal insulation materials are measured by Heat Flow Meter (HFM) apparatus. The components of uncertainty are complex and difficult on routine measurement by modelling approach. In this study, uncertainty of thermal conductivity measurement was estimated by single laboratory validation approach. The within-laboratory reproducibility was 1.1%. The standard uncertainty of method and laboratory bias by using SRM1453 expanded polystyrene board was dominant at 1.4%. However, it was assessed that there was no significant bias. For sample measurement, the sources of uncertainty were repeatability, density of sample and thermal conductivity resolution of HFM. From this approach to sample measurements, the combined uncertainty was calculated. In summary, the thermal conductivity of sample, polystyrene foam, was reported as 0.03367 W/m·K ± 3.5% (k = 2) at mean temperature 23.5 °C. The single laboratory validation approach is simple key of routine testing laboratory for estimation uncertainty of thermal conductivity measurement by using HFM, according to ISO/IEC 17025-2017 requirements. These are meaningful for laboratory competent improvement, quality control on products, and conformity assessment.
Abstract: In soilless culture, the definition of efficient fertigation
strategies is fundamental for the growth of crops. Flexible
test-benches able to independently manage groups of crops are key for
investigating efficient fertigation practices through experimentation.
These test-benches must be able to provide nutrient solution (NS) in a
precise, uniform and repeatable way in order to effectively implement
and compare different fertigation strategies. This article describes
a distribution module for investigating fertigation practices able to
control the fertigation dose and frequency. The proposed solution is
characterized in terms of precision, uniformity and repeatability since
these parameters are fundamental in the implementation of effective
experiments for the investigation of fertigation practices. After a
calibration process, the implemented system reaches a precision of
1mL, a uniformity of 98.5% at a total cost of 735USD.
Abstract: Any industrial company needs to determine the amount of variation that exists within its measurement process and guarantee the reliability of their data, studying the performance of their measurement system, in terms of linearity, bias, repeatability and reproducibility and stability. This issue is critical for automotive industry suppliers, who are required to be certified by the 16949:2016 standard (replaces the ISO/TS 16949) of International Automotive Task Force, defining the requirements of a quality management system for companies in the automotive industry. Measurement System Analysis (MSA) is one of the mandatory tools. Frequently, the measurement system in companies is not connected to the equipment and do not incorporate the methods proposed by the Automotive Industry Action Group (AIAG). To address these constraints, an R&D project is in progress, whose objective is to develop a web and cloud-based MSA tool. This MSA tool incorporates Industry 4.0 concepts, such as, Internet of Things (IoT) protocols to assure the connection with the measuring equipment, cloud computing, artificial intelligence, statistical tools, and advanced mathematical algorithms. This paper presents the preliminary findings of the project. The web and cloud-based MSA tool is innovative because it implements all statistical tests proposed in the MSA-4 reference manual from AIAG as well as other emerging methods and techniques. As it is integrated with the measuring devices, it reduces the manual input of data and therefore the errors. The tool ensures traceability of all performed tests and can be used in quality laboratories and in the production lines. Besides, it monitors MSAs over time, allowing both the analysis of deviations from the variation of the measurements performed and the management of measurement equipment and calibrations. To develop the MSA tool a ten-step approach was implemented. Firstly, it was performed a benchmarking analysis of the current competitors and commercial solutions linked to MSA, concerning Industry 4.0 paradigm. Next, an analysis of the size of the target market for the MSA tool was done. Afterwards, data flow and traceability requirements were analysed in order to implement an IoT data network that interconnects with the equipment, preferably via wireless. The MSA web solution was designed under UI/UX principles and an API in python language was developed to perform the algorithms and the statistical analysis. Continuous validation of the tool by companies is being performed to assure real time management of the ‘big data’. The main results of this R&D project are: MSA Tool, web and cloud-based; Python API; New Algorithms to the market; and Style Guide of UI/UX of the tool. The MSA tool proposed adds value to the state of the art as it ensures an effective response to the new challenges of measurement systems, which are increasingly critical in production processes. Although the automotive industry has triggered the development of this innovative MSA tool, other industries would also benefit from it. Currently, companies from molds and plastics, chemical and food industry are already validating it.
Abstract: The Canadian Used Fuel Container (UFC) is a mid-size hemispherical headed copper coated steel container measuring 2.5 meters in length and 0.5 meters in diameter containing 48 used fuel bundles. The contained used fuel produces significant gamma radiation requiring automated assembly processes to complete the assembly. The design throughput of 2,500 UFCs per year places constraints on equipment and hot cell design for repeatability, speed of processing, robustness and recovery from upset conditions. After UFC assembly, the UFC is inserted into a Buffer Box (BB). The BB is made from adequately pre-shaped blocks (lower and upper block) and Highly Compacted Bentonite (HCB) material. The blocks are practically ‘sandwiching’ the UFC between them after assembly. This paper identifies one possible approach for the BB automatic assembly cell and processes. Automation of the BB assembly will have a significant positive impact on nuclear safety, quality, productivity, and reliability.
Abstract: Recycled glass material is made from 100% recycled bottle glass and consumes less energy than re-melt technology. It also uses no additives in the manufacturing process allowing the recycled glass material, in principal, to go back to the recycling stream after end-of-use, contributing to the circular economy with a low ecological impact. The aim of this paper is to investigate the procedure for testing the recycled glass material for impact resistance, so it can be applied to pavements and other surfaces which are at risk of impact during service. A review of different impact test procedures for construction materials was undertaken, comparing methodologies and international standards applied to other materials such as natural stone, ceramics and glass. A drop weight impact testing machine was designed and manufactured in-house to perform these tests. As a case study, samples of the recycled glass material were manufactured with two different thicknesses and tested. The impact energy was calculated theoretically, obtaining results with 5 and 10 J. The results on the material were subsequently discussed. Improvements on the procedure can be made using high speed video technology to calculate velocity just before and immediately after the impact to know the absorbed energy. The initial results obtained in this procedure were positive although repeatability needs to be developed to obtain a correlation of results and finally be able to validate the procedure. The experiment with samples showed the practicality of this procedure and application to the recycled glass material impact testing although further research needs to be developed.
Abstract: Developing electronic system for detecting low energy impacts using open source hardware such as Arduino is challenging. A highly efficient loadcell is designed and fabricated. A commercial polyvinylidene fluoride (PVDF) piezoelectric film is used as primary sensor for sensing small impacts. Without modifying hardware, the Arduino board is configured by programming to capture the signal from the film sensor with a resolution better than 1.1 mV. By our system, impact energy as low as 1.8 µJ (corresponds to impact force of 39.9 mN) is reliably and monitored. In the linear zone, sensitivity of the system found to be as high as 20.7 kV/J or 3.3 V/N with a measurement frequency of 500 Hz. The various characteristics such as linearity, hysteresis, repeatability and spectrum analysis are discussed. After calibration, measurements of unknown impact energy and impact force are investigated and results are found to agree well.
Abstract: Fabric as the first and most common layer that is in permanent contact with human skin is a very good interface to provide coverage, as well as heat and cold insulation. Phase change materials (PCMs) are organic and inorganic compounds which have the capability of absorbing and releasing noticeable amounts of latent heat during phase transitions between solid and liquid phases at a low temperature range. PCMs come across phase changes (liquid-solid and solid-liquid transitions) during absorbing and releasing thermal heat; so, in order to use them for a long time, they should have been encapsulated in polymeric shells, so-called microcapsules. Microencapsulation and nanoencapsulation methods have been developed in order to reduce the reactivity of a PCM with outside environment, promoting the ease of handling, decreasing the diffusion and evaporation rates. Methods of incorporation of PCMs in textiles such as electrospinning and determining thermal properties had been summarized. Paraffin waxes catch a lot of attention due to their high thermal storage density, repeatability of phase change, thermal stability, small volume change during phase transition, chemical stability, non-toxicity, non-flammability, non-corrosive and low cost and they seem to play a key role in confronting with climate change and global warming. In this article, we aimed to review the researches concentrating on the characteristics of PCMs and new materials and methods of microencapsulation.
Abstract: Noninvasive diagnostics of diseases via breath
analysis has attracted considerable scientific and clinical interest for
many years and become more and more promising with the rapid
advancements in nanotechnology and biotechnology. The volatile
organic compounds (VOCs) in exhaled breath, which are mainly
blood borne, particularly provide highly valuable information about
individuals’ physiological and pathophysiological conditions.
Additionally, breath analysis is noninvasive, real-time, painless, and
agreeable to patients. We have developed a wireless sensor array
based on single-stranded DNA (ssDNA)-functionalized single-walled
carbon nanotubes (SWNT) for the detection of a number of
physiological indicators in breath. Seven DNA sequences were used
to functionalize SWNT sensors to detect trace amount of methanol,
benzene, dimethyl sulfide, hydrogen sulfide, acetone, and ethanol,
which are indicators of heavy smoking, excessive drinking, and
diseases such as lung cancer, breast cancer, and diabetes. Our test
results indicated that DNA functionalized SWNT sensors exhibit
great selectivity, sensitivity, and repeatability; and different
molecules can be distinguished through pattern recognition enabled
by this sensor array. Furthermore, the experimental sensing results
are consistent with the Molecular Dynamics simulated ssDNAmolecular
target interaction rankings. Thus, the DNA-SWNT sensor
array has great potential to be applied in chemical or biomolecular
detection for the noninvasive diagnostics of diseases and personal
health monitoring.
Abstract: This contribution is focused on the methodology for
identifying levels of quality and improving quality through new
logistics model in railway transport. It is oriented on the application
of dynamic quality models, which represent an innovative method of
evaluation quality services. Through this conception, time factor,
expected, and perceived quality in each moment of the transportation
process within logistics chain can be taken into account. Various
models describe the improvement of the quality which emphases the
time factor throughout the whole transportation logistics chain.
Quality of services in railway transport can be determined by the
existing level of service quality, by detecting the causes of
dissatisfaction employees but also customers, to uncover strengths
and weaknesses. This new logistics model is able to recognize critical
processes in logistic chain. It includes service quality rating that must
respect its specific properties, which are unrepeatability,
impalpability, their use right at the time they are provided and
particularly changeability, which is significant factor in the
conditions of rail transport as well. These peculiarities influence the
quality of service regarding the constantly increasing requirements
and that result in new ways of finding progressive attitudes towards
the service quality rating.
Abstract: Since 1920, the industry has almost completely
changed the rivets production techniques for the manufacture of
permanent welding join production of structures and manufacture of
other products. The welding arc is the process more widely used in
industries. This is accomplished by the heat of an electric arc which
melts the base metal while the molten metal droplets are transferred
through the arc to the welding pool, protected from the atmosphere
by a gas curtain. The GMAW (Gas metal arc welding) process is
influenced by variables such as: current, polarity, welding speed,
electrode: extension, position, moving direction; type of joint,
welder's ability, among others. It is remarkable that the knowledge
and control of these variables are essential for obtaining satisfactory
quality welds, knowing that are interconnected so that changes in one
of them requiring changes in one or more of the other to produce the
desired results. The optimum values are affected by the type of base
metal, the electrode composition, the welding position and the quality
requirements. Thus, this paper proposes a new methodology, adding
the variable vibration through a mechanism developed for GMAW
welding, in order to improve the mechanical and metallurgical
properties which does not affect the ability of the welder and enables
repeatability of the welds made. For confirmation metallographic
analysis and mechanical tests were made.
Abstract: The Chair of Thermal Engineering at Poznan
University of Technology has been conducted research works on the
possibilities of using carbon nanostructures in energy and mechanics
applications for a couple of years. Those studies have provided results in a form of co-operation with foreign research centres, numerous publications and patent
applications.
Authors of this paper have studied the influence of multi-walled
carbon nanostructures on changes in static friction arising when steel
surfaces were moved. Tests were made using the original test stand
consisting of automatically controlled inclined plane driven by
precise stepper motors. Computer program created in the LabView
environment was responsible for monitoring of the stand operation,
accuracy of measurements and archiving the obtained results. Such a
solution enabled to obtain high accuracy and repeatability of all
conducted experiments.
Tests and analysis of the obtained results allowed us to determine
how additional layers of carbon nanostructures influenced on changes
of static friction coefficients. At the same time, we analyzed the
potential possibilities of applying nanostructures under consideration
in mechanics.
Abstract: The coaxial transformer-coupled push-pull circuitry
has been used widely in HF and VHF amplifiers for many decades
without significant changes in the topology of the transformers. Basic
changes over the years concerned the construction and turns ratio of
the transformers as has been imposed upon the newer technologies
active devices demands. The balun transmission line transformers
applied in push-pull amplifiers enable input/output impedance
transformation, but are mainly used to convert the balanced output
into unbalanced and the input unbalanced into balanced. A simple
and affordable alternative solution over the traditional coaxial
transformer is the coreless planar balun. A key advantage over the
traditional approach lies in the high specifications repeatability;
simplifying the amplifier construction requirements as the planar
balun constitutes an integrated part of the PCB copper layout. This
paper presents the performance analysis of a planar LDMOS
MRFE6VP5600 Push-Pull amplifier that enables robust operation in
Band III, DVB-T, DVB-T2 standards but functions equally well in
Band II, for DRM+ new generation transmitters.
Abstract: For cycling, the analysis of the pedal force is one of the
important factors in the study of exercise ability assessment and
overuse injuries. In past studies, a two-axis measurement sensor was
used at the sagittal plane to measure the force only in the anterior,
posterior, and vertical directions and to analyze the loss of force and
the injury on the frontal plane due to the forces in the right and left
directions. In this study, which is a basic study on diverse analyses of
the pedal force that consider the forces on the sagittal plane and the
frontal plane, a three-axis pedal force measurement sensor was
developed to measure the anterior-posterior (Fx), medio-lateral (Fz),
and vertical (Fy) forces. The sensor was fabricated with a size and
shape similar to those of the general flat pedal, and had a 550g weight
that allowed smooth pedaling. Its measurement range was ±1000 N for
Fx and Fz and ±2000 N for Fy, and its non-linearity, hysteresis, and
repeatability were approximately 0.5%. The data were sampled at
1000 Hz using a signal collector. To use the developed sensor, the
pedaling efficiency (index of efficiency, IE) and the range of left and
right (medio-lateral, ML) forces were measured with two seat heights
(low and high). The results of the measurement showed that the IE was
higher and the force range in the ML direction was lower with the high
position than with the low position. The developed measurement
sensor and its application results will be useful in understanding and
explaining the complicated pedaling technique, and will enable
diverse kinematic analyses of the pedal force on the sagittal plane and
the frontal plane.
Abstract: In the present work, hydrogen gas sensor of modest
sensitivity utilizing functionalized multiwalled carbon nanotubes
partially decorated with tin oxide nanoparticles (F-MWCNTs/SnO2)
has been fabricated. This sensing material was characterized by
scanning electron microscopy (SEM). In addition, a remarkable
finding was that the F-MWCNTs/SnO2 sensor shows good sensitivity
as compared to F-MWCNTs for low concentration (0.05-1% by
volume) of H2 gas. The fabricated sensors show complete resistance
recovery and good repeatability when exposed to H2 gas at the room
temperature conditions.
Abstract: A total of 150 meat type chickens comprising 50 each
of Arbor Acre, Marshall and Ross were used for this study which
lasted for 10 weeks at the Federal University of Agriculture,
Abeokuta, Nigeria. Growth performance data were collected from the
third week through week 10 and data obtained were analysed using
the Generalized Linear Model Procedure. Heritability estimates (h2)
for body dimensions carried out on the chicken strains ranged from
low to high. Marshall broiler chicken strain had the highest h2 for
body weight 0.46±0.04, followed by Arbor Acre and Ross with h2
being 0.38±0.12 and 0.26±0.06, respectively. The repeatability
estimates for body weight in the three broiler strains were high, and it
ranged from 0.70 at week 4 to 0.88 at week 10. Relationships
between the body weight and linear body measurements in the broiler
chicken strains were positive and highly significant (p > 0.05).
Abstract: The aim of the present work was to test in vitro inhibition of food pathogens and spoilage bacteria by crude bacteriocins from autochthonous lactic acid bacteria. Thirty autochthonous lactic acid bacteria isolated previously, belonging to the genera: Lactobacillus, Carnobacterium, Lactococcus, Vagococcus, Streptococcus, and Pediococcus, have been screened by an agar spot test and a well diffusion assay against Gram-positive and Gram-negative harmful bacteria: Bacillus cereus, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 8739, Salmonella typhimurium ATCC 14028, Staphylococcus aureus ATCC 6538, and Pseudomonas aeruginosa under conditions means to reduce lactic acid and hydrogen peroxide effect to select bacteria with high bacteriocinogenic potential. Furthermore, crude bacteriocins semiquantification and heat sensitivity to different temperatures (80, 95, 110°C, and 121°C) were performed. Another exploratory test concerning the response of St. aureus ATCC 6538 to the presence of crude bacteriocins was realized. It has been observed by the agar spot test that fifteen candidates were active toward Gram-positive targets strains. The secondary screening demonstrated an antagonistic activity oriented only against St. aureus ATCC 6538, leading to the selection of five isolates: Lm14, Lm21, Lm23, Lm24, and Lm25 with a larger inhibition zone compared to the others. The ANOVA statistical analysis reveals a small variation of repeatability: Lm21: 0.56%, Lm23: 0%, Lm25: 1.67%, Lm14: 1.88%, Lm24: 2.14%. Conversely, slight variation was reported in terms of inhibition diameters: 9.58± 0.40, 9.83± 0.46 and 10.16± 0.24 8.5 ± 0.40 10 mm for, Lm21, Lm23, Lm25, Lm14and Lm24, indicating that the observed potential showed a heterogeneous distribution (BMS = 0.383, WMS = 0.117). The repeatability coefficient calculated displayed 7.35%. As for the bacteriocins semiquantification, the five samples exhibited production amounts about 4.16 for Lm21, Lm23, Lm25 and 2.08 AU/ml for Lm14, Lm24. Concerning the sensitivity the crude bacteriocins were fully insensitive to heat inactivation, until 121°C, they preserved the same inhibition diameter. As to, kinetic of growth , the µmax showed reductions in pathogens load for Lm21, Lm23, Lm25, Lm14, Lm24 of about 42.92%, 84.12%, 88.55%, 54.95%, 29.97% in the second trails. Inversely, this pathogen growth after five hours displayed differences of 79.45%, 12.64%, 11.82%, 87.88%, 85.66% in the second trails, compared to the control. This study showed potential inhibition to the growth of this food pathogen, suggesting the possibility to improve the hygienic food quality.
Abstract: Analysis of heart rate variability (HRV) has become a
popular non-invasive tool for assessing the activities of autonomic
nervous system. Most of the methods were hired from techniques
used for time series analysis. Currently used methods are time
domain, frequency domain, geometrical and fractal methods. A new
technique, which searches for pattern repeatability in a time series, is
proposed for quantifying heart rate (HR) time series. These set of
indices, which are termed as pattern repeatability measure and
pattern repeatability ratio are able to distinguish HR data clearly
from noise and electroencephalogram (EEG). The results of analysis
using these measures give an insight into the fundamental difference
between the composition of HR time series with respect to EEG and
noise.