300 research outputs found
Bounded injectivity and Haagerup tensor product
In this paper, we prove that if V ⊆ B(H) is an injective operator system on a separable Hilbert space H, then V ⊗hW is b-injective for any operator system W if and only if V is finite dimensional
A COMPARISON OF ORGANIC AND CHEMICAL FERTILIZERS FOR TOMATO PRODUCTION
Tomato (Lycopersicon esculentum Mill.) is one of the most popular and versatile vegetables in the world, and organic production with a high yield and desirable quality is a target of many producers. The effect of four different fertilizers (chemical, municipal solid waste compost, cattle manure, and spent mushroom compost) on four commercial tomato cultivars (Redstone, Flat, Peto Pride and Chief) was assessed in this research. The highest yield was obtained with the Chief cultivar when fertilized with chemical fertilizer and the lowest value was obtained with Peto Pride fertilized with 20 tonnes per hectare (t/ha) of cow manure. The difference between the two classes of fertilizers (organic and chemical) was not very high so that organic fertilizers are competitive and may be a suitable replacement for chemical fertilizer. According to our results, to achieve maximum yields with organic fertilizers, 20 t/ha of spent mushroom compost can be recommended for the Redstone cultivar, 30 t/ha of cow manure for Flat, 300 t/ha of municipal solid waste compost for Peto Pride, and 300 t/ha of municipal solid waste compost or 20 t/ha of spent mushroom compost can be recommended for the Chief cultivar. These recommended organic fertilizing regimes achieved cultivar yields comparable to the chemical fertilizer treatments, achieving a yield of 98.4% for Redstone, 99.5% for Flat, 97.6% for Peto Pride, and 95.7% for Chief
Solution-processed multiferroic thin-films with large magnetoelectric coupling at room-temperature
Experimental realization of thin films with a significant room-temperature magnetoelectric coupling coefficient, αME, in the absence of an external DC magnetic field, has been thus far elusive. Here, a large coupling coefficient of 750 ± 30 mV Oe-1 cm-1 is reported for multiferroic polymer nanocomposites (MPCs) thin-films in the absence of an external DC magnetic field. The MPCs are based on PMMA-grafted cobalt-ferrite nanoparticles uniformly dispersed in the piezoelectric polymer poly(vinylidene fluoride-co-trifluoroethylene, P(VDF-TrFE). It is shown that nanoparticle agglomeration plays a detrimental role and significantly reduces αME. Surface functionalization of the nanoparticles by grafting a layer of poly(methyl methacrylate) (PMMA) via atom transfer radical polymerization (ATRP) renders the nanoparticle miscible with P(VDF-TRFE) matrix, thus enabling their uniform dispersion in the matrix even in submicrometer thin films. Uniform dispersion yields maximized interfacial interactions between the ferromagnetic nanoparticles and the piezoelectric polymer matrix leading to the experimental demonstration of large αME values in solution-processed thin films, which can be exploited in flexible and printable multiferroic electronic devices for sensing and memory applications.</p
Magnetoelectric coupling coefficient in multiferroic capacitors:Fact vs Artifacts
Multiferroic materials are characterized by their magnetoelectric coupling coefficient, which can be obtained using a lock-in amplifier by measuring the voltage developed across a multiferroic capacitor in a time-variable magnetic field, Hac cos(ωt), where Hac and ω are the amplitude and frequency of the applied magnetic field. The measurement method, despite its simplicity, is subject to various parasitic effects, such as magnetic induction, which leads to significant over-estimation of the actual magnetoelectric response. This article outlines the measurement theory for a multiferroic capacitor using the lock-in technique. It is demonstrated that the inductive contribution has linear proportionality with Hac, ω, and Hacω. It is shown that the true magnetoelectric coupling response is retrieved from the real component of the lock-in signal. Using a polymer-nanoparticle multiferroic composite, the internal consistency of the proposed measurement method is experimentally demonstrated, and it is shown that the actual multiferroic signal can be retrieved using the lock-in technique by removing the magnetic induction contribution from the signal. It is observed that the magnetoelectric voltage shows only a linear dependence with Hac, a saturating behavior with ω, and Hacω. Furthermore, a measurement protocol for reliable reporting of magnetoelectric coupling coefficient has been provided.</p
Solution-processed multiferroic thin-films with large magnetoelectric coupling at room-temperature
Experimental realization of thin films with a significant room-temperature magnetoelectric coupling coefficient, αME, in the absence of an external DC magnetic field, has been thus far elusive. Here, a large coupling coefficient of 750 ± 30 mV Oe-1 cm-1 is reported for multiferroic polymer nanocomposites (MPCs) thin-films in the absence of an external DC magnetic field. The MPCs are based on PMMA-grafted cobalt-ferrite nanoparticles uniformly dispersed in the piezoelectric polymer poly(vinylidene fluoride-co-trifluoroethylene, P(VDF-TrFE). It is shown that nanoparticle agglomeration plays a detrimental role and significantly reduces αME. Surface functionalization of the nanoparticles by grafting a layer of poly(methyl methacrylate) (PMMA) via atom transfer radical polymerization (ATRP) renders the nanoparticle miscible with P(VDF-TRFE) matrix, thus enabling their uniform dispersion in the matrix even in submicrometer thin films. Uniform dispersion yields maximized interfacial interactions between the ferromagnetic nanoparticles and the piezoelectric polymer matrix leading to the experimental demonstration of large αME values in solution-processed thin films, which can be exploited in flexible and printable multiferroic electronic devices for sensing and memory applications.</p
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Fully cognitive transceiver for High Frequency (HF) applications
Ionospheric conditions are variable in nature and can cause destructive interference to transmissions made in the High Frequency (HF) band, which ranges from 3-30 MHz. This poses a problem as the HF band is a critical frequency range for various applications (i.e. emergency, military). To manage these dynamic conditions, intelligent techniques should be implemented at the transmitter and receiver to properly maintain reliable communications. In this paper, we present work deriving components of a cognitive HF transceiver with agents called cognitive engines (CEs) operating at the transmitter and receiver. At the transmitter, cognition is employed to determine the combination of modulation and coding techniques that maximize throughput. At the receiver, cognition is implemented to derive the best parameters for equalization (i.e. tap length, step size, filter type, etc.) Results are presented showing that the individual components are able to satisfy their objectives. A discussion is also provided surveying recent research efforts pertaining to the development of cognitive methods for the Automatic Link Establishment (ALE) protocol, a common networking methodology for HF stations.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Soil stabilisation with alkali-activated agro-waste
This study addresses the use of alkali-activated binder to evaluate the feasibility of using this promising technique to stabilise soils. One of the well-known agro-wastes, palm oil fuel ash (POFA), was used as a source binder. Also, sodium hydroxide (NaOH) and potassium hydroxide (KOH) were used as alkaline activators. The influence of four factors including the kind of alkaline activator, the use of source binder, the curing condition and the water content of the soil on the strengthening performance of soil was evaluated according to the improvement of the unconfined compression strength (UCS). At the same alkaline concentration, both sodium hydroxide and potassium hydroxide were able to enhance the strength development rate of specimens. However, potassium hydroxide-POFA-stabilised soil yielded the highest UCS value following a long curing time (90 and 180 d of curing). The size and charge density of the alkaline activator play significant roles in controlling the rate and extent of the activation process for the strength performance. With regard to soil strength improvement, when the POFA content in the activation process increased from 0% to 15%, the UCS value increased substantially, irrespective of the alkaline activator type. This achievement implies a tremendous effect of this agro-waste on the strength behaviour of treated soil
Muscle Activity Correlation With Surgeons’ Self-Reported Workload And Performance In Robotic Training
Studies have shown that muscle activity levels reflect work demands of operators performing physically and mentally tasks. Identifying work demands during the robotic surgery training is essential to ensure usability of teleoperation equipment and prevent surgeon musculoskeletal injuries and fatigue. The purpose of this project is to use physiological muscle activity sensors (electromyography (EMG)) to measure surgeons’ work demands during robotic training and to quantify the relationship of these metrics. Eight surface EMG sensors were used to collect upper body muscle activity. Signals from eight participants (all right-hand dominant) during multiple training sessions were collected while performing simulated robotic assisted tasks on the da Vinci skills simulator. Subjective workload measurements (i.e. NASA-TLX) and performance scores were also collected. The results showed muscle activity for neck, shoulder, and left forearm are significantly correlated with self-perceived workload (p\u3c0.05), especially the left forearm. This may be due to the usage (e.g., holding objects steady) or lack of positioning awareness of participants’ non-dominant hand during the training. The results also showed left bicep activity is negatively correlated with performance score, which suggests that participants’ non-dominant arm training and usage may lead to higher performance score. These results provide insight to surgeons’ workload and to help optimize their performance
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