Tuning Interparticle Hydrogen Bonding in Shear-Jamming Suspensions: Kinetic Effects and Consequences for Tribology and Rheology

The shear-jamming of dense suspensions can be strongly affected by molecular-scale interactions between particles, e.g. by chemically controlling their propensity for hydrogen bonding. However, hydrogen bonding not only enhances interparticle friction, a critical parameter for shear jamming, but also introduces (reversible) adhesion, whose interplay with friction in shear-jamming systems has so far remained unclear. Here, we present atomic force microscopy studies to assess interparticle adhesion, its relationship to friction, and how these attributes are influenced by urea, a molecule that interferes with hydrogen bonding. We characterize the kinetics of this process with nuclear magnetic resonance, relating it to the time dependence of the macroscopic flow behavior with rheological measurements. We find that time-dependent urea sorption reduces friction and adhesion, causing a shift in the shear-jamming onset. These results extend our mechanistic understanding of chemical effects on the nature of shear jamming, promising new avenues for fundamental studies and applications alike

Keterkaitan Karakteristik Kawasan Transit Berdasarkan Prinsip Transit Oriented Development (TOD) terhadap Tingkat Penggunaan Kereta Komuter Koridor Surabaya-Sidoarjo

Koridor Surabaya-Sidoarjo telah dilayani dengan kereta komuter dalam mendukung tulang punggung transportasi perkotaan Surabaya. Namun penggunaan moda ini belum optimal. Hal ini dilihat dari besarnya pergerakan penduduk yang masih didominasi oleh penggunaan kendaraan pribadi menyebabkan kemacetan. Untuk mengatasi permasalahan tersebut diperlukan strategi inovatif yang mengedepankan integrasi antara penggunaan lahan dengan transportasi, salah satunya melalui konsep Transit Oriented Development (TOD) di kawasan stasiun kereta di sepanjang koridor Surabaya-Sidoarjo. Sebagai upaya pengimplementasiannya, perlu dilakukan studi mengenai keterkaitan karakteristik kawasan transit berbasis TOD terhadap jumlah penggunaan kereta komuter koridor Surabaya-Sidoarjo. Melalui analisis korelasi diperoleh hasil penelitian bahwa kepadatan penggunaan lahan (KLB), index keberagaman guna lahan (mixed use entrophy index) perdagangan dan jasa dan fasilitas umum, rata-rata lebar jalur pejalan kaki, dan luas jalur pejalan kaki signifikan memiliki hubungan korelasi yang kuat dengan tingkat penggunaan kereta komuter. Hal ini menunjukkan bahwa adanya potensi pengembangan kawasan transit berbasis TOD pada koridor Surabaya-Sidoarjo dalam mendorong penggunaan kereta komuter

Influence of yarn parameters on cotton/kenaf blended yarn characteristics

Spinning kenaf fibers into yarns is challenging due to the stiffness and lack of cohesiveness of the fibers. Alkali treatment is known to remove hemicellulose, wax, and breaks down lignin, reducing stiffness of kenaf fiber and improving its spinnability. Kenaf fibers were treated at percentages of 4% and 6% and blended with cotton fibers at blend ratios of 40:60 and 50:50 prior to a ring spinning process to produce a double ply yarn of 70 tex. Yarn were twisted at three sets of twist. The responses were measured in terms of carding waste percentages and yarn strength. The results showed that the optimized yarn structural parameter is kenaf fiber treated at 6% and with a kenaf/cotton 40/60 blending ratio based on its tenacity and minimum carding waste. ANOVA shows that there is a good interaction effect between NaOH and kenaf/cotton ratio, and NaOH concentration and twist

Perbandingan Pengukuran Konsentrasi Partikulat di Udara Ambien Menggunakan Alat High Volume Air Sampler dan Gent Stacked Filter Unit Sampler

Pengambilan contoh uji partikulat di udara ambien dapat dilakukan dengan menggunakan peralatan yang berbeda yaitu High Volume Air Sampler (HVAS) dan Gent Stacked Filter Unit Sampler. Untuk mengetahui hasil dari kedua metode sampling tersebut, Pusarpedal melakukan pengambilan contoh uji menggunakan kedua alat tersebut dan mengukur parameter logam berat timbal (Pb) sesuai yang tercantum di dalam Lampiran Peraturan Pemerintah No. 41 Tahun 1999 tentang Pengendalian Pencemaran Udara. Penelitian ini bertujuan untuk mendapatkan rasio atau perbandingan konsentrasi Pb yang didapat dari alat HVAS dan Gent stacked filter unit sampler. Contoh uji Total Suspended Particulate (TSP) yang didapat dari alat HVAS merupakan partikel yang berada pada ukuran 0-100μm, dan analisis kandungan logam timbal (Pb) dalam sampel ini dilakukan menggunakan Atomic Absorption Spectrometry (AAS). Sedangkan pada alat Gent Stacked Filter Unit Sampler ukuran partikel yang diperoleh adalah dua jenis partikel yang berukuran 0-2,5μm atau PM2.5 dan ukuran partikel 2,5-10μm atau PM2.5-10. Analisis Pb pada sampel ini dilakukan menggunakan Particle Induced X-ray Emission (PIXE). Hasil pengukuran yang dilakukan pada rentang waktu 25 Agustus sampai 25 September 2008 menunjukkan konsentrasi Pb pada PM2,5-10 memiliki korelasi yang cukup kuat atau mempunyai pola kecenderungan yang sama terhadap konsentrasi Pb di TSP dengan nilai R2 sekitar 0,7

Model Sistem Tagihan Listrik dan Pengendali Arus dengan Menggunakan Sensor Arus

KWh meter merupakan suatu alat yang menghitung jumlah pemakaian listrik yang mengalir melewatinya. Permasalahannya total pemakaian listrik yang tertera pada kWh meter masih dalam satuan kWh, pembatasan arus listrik menggunakan MCB. Perancangan model sistem billing listrik dan pengendalian arus bertujuan untuk mengatasi permasalahan tersebut, yaitu dengan membuat sebuah alat yang dapat berfungsi sebagai penghitung jumlah pemakaian listrik yang sudah dikonversi kedalam satuan rupiah, sekaligus dapat membatasi arus yang dapat mengalir ke beban. Perancangan ini terdiri dari modul sensor arus, modul ADC, modul mikrokontroler, modul interface, modul relay, dan menggunakan komputer sebagai pengendali alat ini. Hasil pengujian menunjukkan alat ini dapat berfungsi sesuai dengan yang diharapkan untuk berfungsi sebagai sistem billing sekaligus pengendali arus

Technique for early reliability prediction of software components using behaviour models

Behaviour models are the most commonly used input for predicting the reliability of a software system at the early design stage. A component behaviour model reveals the structure and behaviour of the component during the execution of system-level functionalities. There are various challenges related to component reliability prediction at the early design stage based on behaviour models. For example, most of the current reliability techniques do not provide fine-grained sequential behaviour models of individual components and fail to consider the loop entry and exit points in the reliability computation. Moreover, some of the current techniques do not tackle the problem of operational data unavailability and the lack of analysis results that can be valuable for software architects at the early design stage. This paper proposes a reliability prediction technique that, pragmatically, synthesizes system behaviour in the form of a state machine, given a set of scenarios and corresponding constraints as input. The state machine is utilized as a base for generating the component-relevant operational data. The state machine is also used as a source for identifying the nodes and edges of a component probabilistic dependency graph (CPDG). Based on the CPDG, a stack-based algorithm is used to compute the reliability. The proposed technique is evaluated by a comparison with existing techniques and the application of sensitivity analysis to a robotic wheelchair system as a case study. The results indicate that the proposed technique is more relevant at the early design stage compared to existing works, and can provide a more realistic and meaningful prediction

The New Notion Distance of Content Based Image Retrieval (Cbir)

This paper proposes a new notion distance on the CBIR process whichis derived from the measure of multivariate dispersion called vector variance (VV).The minimum vector variance (MVV) estimator is robust estimator having the highbreakdown point. The CBIR is a retrieval technique using the visual informationby retrieving collections of digital images. The process of retrieval is carried outby measuring the similarity between query image and the image in the databasethrough similarity measure. Distance is a metric often used as similarity measureon CBIR. The query image is relevant to an image in the database if the value ofsimilarity measure is \u27small\u27. This means that a good CBIR retrieval system mustbe supported by an accurate similarity measure. The classical distance is generatedfrom the arithmetic mean which is vulnerable to the masking e®ect. The appearanceof extreme data causes the in°ation of deviation of the arithmetic mean, this impliesthe distance between the extreme data or the outlier becomes closer than it supposedto be. In the end of section we discuss the high performance of the MVV robustdistance to CBIR process.DOI : http://dx.doi.org/10.22342/jims.16.1.31.51-6

Analysis of signal propagation in an experiment room with epoxy covered floor for wireless sensor network applications

As sensor applications combined with wireless network becoming more of an everyday applications, the optimal deployment becomes ever increasing important as that would be a key important factor in the trade-off between cost and link quality. This paper reports on the effect of epoxy covered floor on signal propagation characteristics in an experiment room. Microchip developed motes were used to measure signal propagation in an experiment room where sensors would be deployed extensively. The results show that the signal strength for 30 cm antenna height provides a significant margin with respect to signal noise floor. As for the 5 cm antenna height, there is still around 25 dB margin in average before the signal reaches noise floor. Analysis shows that the log-distance model is the best fit to the measured data. Free Space Loss model seemed to under estimate the overall performance of the signals. An important conclusion from this study is that wireless mote deployment must consider the margin between the two signals of antenna heights and the margin to noise floor to avoid link quality deterioration especially for sensitive data acquisition applications

Prokinetics Prescribing in Paediatrics: Evidence on Cisapride, Domperidone, and Metoclopramide

Objectives: Domperidone and metoclopramide are prokinetics commonly prescribed off-label to infants and younger children in an attempt to treat gastro-oesophageal reflux symptoms. Another prokinetic drug, cisapride, was used but withdrawn in 2000 in the United Kingdom because of serious arrhythmic adverse events. Medicines and Healthcare Products Regulatory Agency issued safety warnings for domperidone in May 2012 and restricted its indications. We report here national primary care prescribing trends and safety signals of these drugs in children. Methods: We used data from the General Practice Research Database between 1990 and 2006 for children <18 years. Descriptive statistics and Poisson regressions were performed to characterise prescribing trends. We examined safety signals in nested case–control studies. Results: The proportion of children <2 years old being prescribed one of the medications doubled during the study period. Prescriptions of domperidone increased 10-fold, mainly following the withdrawal of cisapride in 2000. Prescriptions of metoclopramide did not change significantly. Despite the increase in prescriptions of domperidone, no new safety signals were identified. Conclusions: These data showed dramatic changes in prescribing of cisapride and domperidone despite the lack of good-quality supporting evidence. It is possible that these prescribing trends were influenced by published guidelines. Even if produced without robust efficacy and safety evidence, published guidelines can influence clinicians and consequently affect prescribing. Therefore, improving the evidence base on prokinetics to inform future guidelines is vital. The lack of new safety signals during this period would support the development of suitable powered clinical studies