1,429 research outputs found
Use of the local-global concept in detecting component vibration in reactors
The local-global concept, based on the detector adjoint function, was used to develop the response of a detector to an absorber vibrating in one dimension. A one-dimensional two-group diffusion code was developed to calculate the frequency dependent detector response as a function of detector and absorber positions for the coupled-core UTR-10 reactor. Results from this code indicated the best possible detector and absorber locations, where more detailed calculations were made using a two-group, three-dimensional diffusion code with finite detector and absorber volumes. An experiment was then designed, for the chosen positions, using a vibrating cadmium absorber with a detector on each side. The assembly was placed in the vertical central stringer of the reactor. Investigations were carried out for vibrations in two flux gradients and experimental data were analyzed in the frequency domain using a microcomputer based data acquisition system;The experimental investigation showed the validity of the local-global concept. A normalized outputs cross power spectral density was developed that correctly predicted the different flux tilts in the two flux gradients. It was also shown that the frequency response of the local component had a wide plateau region. Monitoring the behavior of the normalized cross power spectral density was thought to be a promising indicator for the detection and localization of malfunctioning vibrating components. It might also be used to detect flux irregularities in the vicinity of a vibrating component
The effect of customer satisfaction on parcel delivery operations using autonomous vehicles: An agent-based simulation study
The quality of Third-Party Logistics (3PL) services represented by delivery time decides the outcome of customer satisfaction. The result of this satisfaction judges the type of Word of Mouth (WoM) that, if positive, plays a vital role in attracting non-customers who are willing in 3PL services to join as customers. In this paper, we investigate the effect of an essential factor represented by Word of Mouth on the number of customers in 3PL companies. Therefore, an agent-based model for parcel delivery is developed to investigate the impact of social factors such as WoM and other operational factors, including vehicle number and speed, on customer number and satisfaction, average service time, and vehicle utilization. As a methodology, state charts of Vehicle, Customer, Hub agents are developed to mimic the messaging protocols between these agents under the WoM concept. A case study based in 3PL in Jordan is used as a test bench of the developed model. A sensitivity analysis study is conducted to test the developed model's performance, including different levels of influential model parameters such as targeting non-customers parameters by Loyal/Unhappy customers. Key results reveal that the best scenario is achieved when the WoM value equals 10, the vehicle number equals 30, and the vehicle speed equals 60 km/h. These model parameters result in higher customer numbers of 873, vehicle utilization equals 63%, and customer satisfaction equals 99%. Video of our proposed model showing it in action can be found at: https://www.youtube.com/watch?v=3rR4l130-QU
The interrelation between the perception and production of English monophthongs by speakers of Iraqi Arabic
The assumption that performance in second language (L2) speech perception and speech production is aligned has received much debate in L2 research. Theoretical models such as the Motor Theory (MT) and Speech Learning Model (SLM) have described the relation between these two processes based on the assumption that speech is perceived with reference to how it is produced and speech production is in turn influenced by how well speech contrast is perceptible to the second-language learner. The present study aims to investigate this relation with regard to Iraqi learners' perception and production of English vowels, focussing on the role of L1 interference and English proficiency level in shaping this relation. The results of the present study showed that accurate perception may not necessarily be a prerequisite for accurate production especially for EFL learners at the elementary level. Perception and production score means were significantly different, revealing an asymmetrical relation between the two processes. The results showed that speech production of L2 learners at the elementary level exceeded their ability in speech perception. However, for the other three proficiency levels, perception and production seemed to develop in synchrony. The level of difficulty encountered in the perception and production tasks could be attributed to L1 interference, since the vowels that were better produced than perceived are all found in the L1 vowel system, while the only vowel that was better perceived is not in the L1 vowel system
A novel optimal small cells deployment for next-generation cellular networks
Small-cell-deployments have pulled cellular operators to boost coverage and capacity in high-demand areas (for example, downtown hot spots). The location of these small cells (SCs) should be determined in order to achieve successful deployments. In this paper, we propose a new approach that optimizes small cells deployment in cellular networks to achieve three objectives: reduce the total cost of network installation, balancing the allocation of resources, i.e. placement of each SC and their transmitted power, and providing optimal coverage area with a lower amount of interference between adjacent stations. An accurate formula was obtained to determine the optimum number of SC deployment (NSC). Finally, we derive a mathematical expression to calculate the critical-handoff-point (CHP) for neighboring wireless stations
ACOUSTIC ANALYSIS OF THE LENGTH OF /ʃ/ AND /Ʒ/ IN ENGLISH AFFRICATES
To participate in the ongoing debate of whether affricates are single phonemes or a combination of two distinct phonemes, this paper reports the results of an acoustic study of affricates. One of the arguments that supports one phoneme analysis is based on the assumption that the length of /ʃ/ and /Ʒ/ as single phonemes tends to be shorter when they are involved within the affricates /ʃ/ and /Ʒ/ respectively. However, this assumption has not been acoustically investigated. Thus, this paper measures the duration of /ʃ/ and /Ʒ/: first when they are alone, and second when they are involved in affricates to identify any length variation between the two cases. The study is based on acoustic and statistical analyses of the recordings of Iraqi, British and American speakers of English, who were asked to pronounce words that have the two fricatives /ʃ/ and /Ʒ/ alone and in affricates as well. The results of paired samples t-tests showed a significant difference in the length of /ʃ/ and /Ʒ/ as single phonemes and their length when involved within affricates in the pronunciation of Iraqi, British and American speakers both on the group and the overall levels. These results support the one phoneme analysis of affricates. Moreover, the results indicated that Arab learners and Iraqis in particular count heavily on temporal cues rather than spectral cues in perceiving English sounds. This shows the need for more training on the part of learners and teachers, and more attention on the part of English textbook designers
Investigating IoT Middleware Platforms for Smart Application Development
With the growing number of Internet of Things (IoT) devices, the data
generated through these devices is also increasing. By 2030, it is been
predicted that the number of IoT devices will exceed the number of human beings
on earth. This gives rise to the requirement of middleware platform that can
manage IoT devices, intelligently store and process gigantic data generated for
building smart applications such as Smart Cities, Smart Healthcare, Smart
Industry, and others. At present, market is overwhelming with the number of IoT
middleware platforms with specific features. This raises one of the most
serious and least discussed challenge for application developer to choose
suitable platform for their application development. Across the literature,
very little attempt is done in classifying or comparing IoT middleware
platforms for the applications. This paper categorizes IoT platforms into four
categories namely-publicly traded, open source, developer friendly and
end-to-end connectivity. Some of the popular middleware platforms in each
category are investigated based on general IoT architecture. Comparison of IoT
middleware platforms in each category, based on basic, sensing, communication
and application development features is presented. This study can be useful for
IoT application developers to select the most appropriate platform according to
their application requirement
Glaucoma and Corneal Transplant Procedures
Glaucoma after corneal transplantation is a leading cause of ocular morbidity after penetrating keratoplasty. The incidence reported is highly variable and a number of etiologic factors have been identified. A number of treatment options are available; surgical intervention for IOP control is associated with a high incidence of graft failure. IOP elevation is less frequently seen following deep anterior lamellar keratoplasty. Descemet's striping-automated endothelial keratoplasty is also associated with postprocedure intraocular pressure elevation and secondary glaucoma and presents unique surgical challenges in patients with preexisting glaucoma surgeries. Glaucoma exists in up to three-quarters of patients who undergo keratoprosthesis surgery and the management if often challenging. The aim of this paper is to highlight the incidence, etiology, and management of glaucoma following different corneal transplant procedures. It also focuses on the challenges in the diagnosis of glaucoma and intraocular pressure monitoring in this group of patients
SYNTHESIS, ANTIMICROBIAL EVALUATION, DENSITY FUNCTIONAL THEORY, AND DOCKING STUDIES OF SOME NEW 2-MERCAPTO PYRIMIDINE SCHIFF BASES
Objective: Pyrimidine derivatives are reported to possess antibacterial, antifungal, anticancer, and anticonvulsant activities. Encouraged by this remarks, we decided to synthesize novel compounds of new 2-macraptopyrimidine linked to Schiffs̕ bases.
Methods: The present work involves the synthesis of new 2-mercaptopyrimidine linked to Schiffs̕ bases. The starting, 2-mercaptopyrimidine, compound (1) reacted with thiourea to afford the corresponding 1-(pyrimidin-2-yl) thiourea (2). Then compound (2) was used as the key intermediate to prepare the -1-(2-hydroxy benzylidene)-3-(pyrimidin-2-yl) thiourea (3), and (1-benzylidine)-3-(pyrimidin-2-yl) thiourea (4), through the reaction with 2-hydroxybenzaldehyde, and benzaldehyde, respectively.
Results: All the synthesized compounds were characterized by Fourier-transform infrared and1H-nuclear magnetic resonance spectroscopy. The synthesized derivatives were screened for their in vitro, antibacterial activity against two Gram-positive bacteria: Bacillus subtilis and Staphylococcus aureus and four Gram-negative bacteria: Klebsiella pneumoniae, Escherichia coli, and Salmonella typhi, and the results showed that most of them have good antibacterial activity. While their antifungal activity against three fungi species (Aspergillus fumigates, Aspergillus niger, Aspergillus terrus and Rhizopus) revealed that compounds (2-4) displayed the most potent antifungal activity. Density functional theory (DFT) calculations for the synthesized 2-mercapto pyrimidine derivatives were conducted, using a molecular structure with optimized geometry. Highest occupied molecular orbital/lowest unoccupied molecular orbital energies and structures are demonstrated.
Conclusion: The antimicrobial activity indicates that compounds (3) and (4) are the most active than the compounds (1) and (2). Molecular docking revealed that compounds (3) and (4), with bulky phenyl groups are essential to blocking the active centers of glucose -6-phosphate synthase in the bacteria and fungi
Optimization of fuzzy photovoltaic maximum power point tracking controller using chimp algorithm
In this paper, a photovoltaic (PV) fuzzy maximum power point tracking (MPPT) method optimized by the chimp algorithm is presented. The fuzzy logic controller (FLC) of seven triangular membership functions (MFs) is used. The optimization fitness function is composed of transient and steady-state indices under different irradiation and temperature operating conditions. By using MATLAB package, the performance of optimized method is examined and compared with asymmetrical FLC and well-known perturb and observe (P&O) tracking methods at different operating conditions in terms of: transient rising time (tr) and energy yield during 30 s. Moreover, the tracking methods are also compared in terms of the fitness function value. From the comparison of simulation results, a more energy can be harvested by using the proposed optimized tracking method compared to the other methods. Consequently, at the various operating conditions, the proposed method can be used as a more reliable tracking method for PV systems
Simultaneous Determination of Piroxicam and Codeine Phosphate Hemihydrate in a Pharmaceutical Dosage Form Using Validated HPLC Method
تم تطوير وتوثيق طريقة تحليلية من أجل التعيين المتواقت لمادتي البيروكسيكام والكودئين فوسفات باستخدام كروماتوكرافيا العمود السائلة عالية الأداء (HPLC) حيث تتمتع هذه الطريقة بالبساطة، الانتقائية والدقة. حُقّق الفصل الاستشرابي بواسطة استخدام عمود الفصل C18 من نوع (BDS Hypersil 5μ, 150 mm x 4.6 mm) واستُخدم الميتانول: وقاء فُسفاتي (4:6 حجم/حجم، pH=2.3) كطور متحرك بمعدل جريان 1.1 مل/دقيقة واستخدم طول موجة مكشاف 214 نانومتر. أُجريت اختبارات ملاءمة النظام لتقييم مدى ملاءمة وفعالية النظام الاستشاربي بأكمله. حُسب زمن احتباس مادتي البيروكسيكام والكودئين فوسفات فكانتا 3.95 و1.460 دقيقة، على التوالي. وأجُري التحقق من مصدوقية الطريقة التحليلية المطورة من حيث الخطية والدقة والمضبوطية والنوعية وحد الكشف وحد التقدير الكمي. حيث كان حد الكشف وحد الكم لمادة البيروكسيكام 1.92 مكغ/مل و6.336 مكغ/مل، على التوالي. أما حد الكشف وحد الكم لمادة الكودئين فوسفات فكانتا 0.29 مكغ/مل و0.95 مكغ/مل، على التوالي. أظهرت كلا المادتين الدوائيتين استجابة خطية ضمن المجال 5-50 مكغ/مل. تهدف هذه الدراسة إلى تطوير طريقة تحليلية باستخدام جهاز الاستشراب عالي الأداء والتحقق من مصدوقيتها، ويمكن استخدام الطريقة المقترحة لتقدير هذه الأدوية في الأشكال الجرعية التوليفية لها.An easy, eclectic, precise high-Performance Liquid Chromatographic (HPLC) procedure was evolved and validated to estimate of Piroxicam and Codeine phosphate. Chromatographic demarcation was accomplished on a C18 column [Use BDS Hypersil C18, 5μ, 150 x 4.6 mm] using a mobile phase of methanol: phosphate buffer (60:40, v/v, pH=2.3), the flow rate was 1.1 mL/min, UV detection was at 214 nm. System Suitability tests (SSTs) are typically performed to assess the suitability and effectiveness of the entire chromatography system. The retention time for Piroxicam was found to be 3.95 minutes and 1.46 minutes for Codeine phosphate. The evolved method has been validated through precision, limit of quantitation, specificity, limit of detection linearity and accuracy. (LOD) was 1.92 mg/mL and (LOQ) was 6.336 mg/mL for Piroxicam, whereas (LOD) for Codeine phosphate was 0.29 mg/mL and (LOQ) was 0.95 mg/mL. Piroxicam and Codeine phosphate showed a linear signal in the domain of 5-50 µg/mL for each compound. This research presided to evolve and validate an HPLC method, and the proposed procedure can be used to estimate these drugs in their combined dosage forms
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