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Development of nanoengineered thulium doped fiber laser with low threshold pump power and tunable operating wavelength

Development of nanoengineered thulium doped fiber laser with low threshold pump power and tunable operating wavelength

length requires the lowest threshold pump power for lasing. As shown in the figure, the operat- ing wavelength of the laser could be continuously tuned from 1890 nm to 1910 nm. The optical signal-to-noise ratio for each spectrum is better than 43 dB. The measured output power char- acteristic with respect to the operating pump power is shown in Fig. 9 for various operating wavelengths. The slope efficiency of the laser varies from 16.4 to 19.7% as the operating wave- length is tuned from 1890 to 1910 nm. The highest slope efficiency of 19.7% is obtained at 1910 nm with 82.8 mW output power at 1100 mW pump power. The tunability of the laser could be extended to a wider range should another tunable FBG with a wider range is used. The slope efficiency of the tunable laser can also be improved by reducing the insertion loss of the tunable filter. The modal properties of the TDF will be investigated in future work since the multimode character of lasing should affect its the laser performances in term of efficiency, stability, etc. The further optimization of the TDF structure and doped ion compositions are also expected to improve the slope efficiency of the laser.
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Photoinduced femtosecond formation of ferromagnetism in a strongly correlated antiferromagentic manganite

Photoinduced femtosecond formation of ferromagnetism in a strongly correlated antiferromagentic manganite

chain hopping with opposite spin alignment, which is weak in the ground state and forbidden for classical spins because of the large  Hund’s  energy  and  small orbital overlap between two chains. Below the threshold of the magnetic phase transition, the inter-spin-chain charge transfer results in an itinerant electron antiferromagnetically coupled with a ferromagnetic spin chain, which leads to the formation of magnetic polarons - a collective state favouring short range ferromagnetic alignment. The ps, slow magnetization rise observed reflects dynamics of such polaron-like collective photoexcitations, which show comparable formation time to those in magnetic semiconductors [7-8]. However, these magnetic polaron-like states are uncorrelated below the excitation threshold where a long-range ferromagnetic phase is absent. Increasing the photoexcitation from the linear to the highly nonlinear regime of the CO/OO melting, the sizes of the ferromagnetic clusters grow nonlinearly and exceed the critical size for percolative phase transition at the threshold pump fluence. A global conducting path of e g electrons emerges and leads to a long
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Steady state and transient Brillouin gain in narrow band-gap magnetized semiconductors

Steady state and transient Brillouin gain in narrow band-gap magnetized semiconductors

Out of the several NLO effects, the nonlinear scattering of laser radiation in gaseous and solid state plasmas aroused a great deal of interest in the past few years [1-5] on account of the fact that the absorption of laser radiation in plasma greatly depends on these processes. When an intense light beam interacts with an active medium, strong optical amplification of the scattered wave occurs at Stoke’s shifted frequency. Such phase coherent processes are called stimulated scattering processes. Amongst these, the study of stimulated Brillouin scattering (SBS) in solids has been the subject of intensive investigations (both theoretical and experimental) due to its manifold technological applications in a wide range of optical communication and optoelectronics applications. Some of these are: distributed fiber optic Brillouin sensors, laser induced fusion, pulse squeezing and optical phase conjugation (OPC) [6]. In laser- induced fusion experiments, SBS is of great concern because it can significantly redirect the pump energy away from the target and thus adversely affects the energy absorption [7]. It is, therefore, desirable to minimize SBS process in these experiments. For OPC, SBS is preferred over other stimulated scattering processes because it initiates at low threshold pump intensity, suffers negligible frequency shifts and offers high conversion efficiency [8]. In this method, the incident wave serves as both the pump for inciting the nonlinear process and distorted wave to be conjugated. Il’ichey [9] has reported that the OPC-SBS conversion efficiency can be expressed in terms of parameters of the scattering medium and excitation intensity. Using a frequency doubled Nd: YAG laser as a pump and Rhodamine 6G as a Brillouin medium, it was experimentally demonstrated that OPC-SBS reflectivity is maximum only at a specific intensity of an incident pump beam [10]. The combination of SBS and four-wave mixing (FWM), termed Brillouin-enhanced four-wave mixing (BEFWM), has recently received great attention as it can yield phase conjugate signals with extremely high reflectivity [11].
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Plasmon-Transverse Optical Phonon Interaction Based Modulational Amplification In Weakly-Polar Magnetoactive Doped Iii-V Semiconductors

Plasmon-Transverse Optical Phonon Interaction Based Modulational Amplification In Weakly-Polar Magnetoactive Doped Iii-V Semiconductors

Abstract: Using the hydrodynamic model of plasmas and considering the origin of nonlinear interaction in third-order optical susceptibility arising from nonlinear induced current density of the medium, a detailed analytical investigation of plasmon-transverse optical phonon interaction based modulational amplification in weakly-polar magnetoactive doped III-V semiconductors. Following the coupled mode approach, expressions for necessary threshold pump amplitude for the onset of modulational amplification and growth rate of modulated wave have been obtained. Numerical estimations made for n-InSb-CO 2 laser system reveals that the threshold pump amplitude can be lowered whereas the growth rate of modulated wave
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1.7MW Nd:YAG Laser Pulse Generation by A Passive BDN Q-switch

1.7MW Nd:YAG Laser Pulse Generation by A Passive BDN Q-switch

switching efficiency, η , expected. Increasing initial transmission leads to average power enhancement and reduction of peak power. It is worth mentioning that initial transmission enhancement of Q-switch, cause less threshold pump energy as a result of less cavity losses. To summarize, at the initial transmission 18.4%, we have obtained the least pulse duration of 27ns with the peak power of 1.7MW. We have obtained the best Q- switched efficiency of 77% with the 31 pulses

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Supermode density wave polariton condensation with a Bose Einstein condensate in a multimode cavity

Supermode density wave polariton condensation with a Bose Einstein condensate in a multimode cavity

has an antinode at the centre of the cavity, whereas the l þ m ¼ 1 mode has a node. The overall higher threshold of the odd mode is indicative of the worse overlap between the atomic wavefunction and the node of the optical mode. The greater rate of threshold increase with pump power ramp rate indicates that the atoms need more time to adapt to the sign-flip of the odd mode than can be provided during the timescale of the faster ramp. Higher threshold pump power is needed to compensate. A consequence of this can be seen in the slow turn-on of superradiance in the data of Fig. 7b. This dynamical effect hints that motion of the atoms following the turn-on of the cavity light may in some cases lead to effects beyond the linear stability analysis presented in the Methods section, which produced the green curve in Fig. 2m. (b) An analogous behaviour is seen in the l þ m ¼ 2 family, for the TEM 02 (blue) and TEM 11 (red) modes. The former has an antinode at the cavity centre, whereas the latter, although still an even-parity mode, has a node at
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Formation of a macroscopically occupied polariton state in a tunable open-access microcavity under resonant excitation

Formation of a macroscopically occupied polariton state in a tunable open-access microcavity under resonant excitation

strengths. Overall, the model parameters were chosen in such a way that the confined polariton energies and the excitation conditions match closely those in the experi- ment. Finally, we use a Runge-Kutta algorithm (see e.g. Ref. 34) to simulate the dynamics of the GP equation. We start from an empty system, turn on the pump and reach a steady state situation. At this point we evalu- ate the spectra of the emitted light and derive the ra- tio between the population at the LG 00 energy and the

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Pumping Solutions for Steam Assisted Gravity Drainage (SAGD) Innovation, Design, Manufacture + Aftermarket

Pumping Solutions for Steam Assisted Gravity Drainage (SAGD) Innovation, Design, Manufacture + Aftermarket

steaM flow oIl sanDs forMatIon SAGD operators are increasingly turning to lift pumps to optimise production rates. However, the downhole pumping environment is the most challenging one in the oil industry, characterised by very high temperatures and aggressive fluids. ClydeUnion Pumps high reliability HSP hydraulic drive pump offers an alternative to the often short lived electric submersible pump (ESP) technology. Field experience shows that the water turbine driven HSP can achieve mean time to failure (MTTF) around three times greater than the industry average for ESPs, which provides the opportunity for reductions in work over frequency, costs and deferred oil production.
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Mathematical Model of Cell Growth for Biofuel Production under Synthetic Feedback

Mathematical Model of Cell Growth for Biofuel Production under Synthetic Feedback

In this paper, mathematical model for cell growth and biofuel production under synthetic feed- back loop is discussed. The nonlinear differential equations are solved analytically for the maxi- mum production of biofuel under synthetic feedback. The closed-form of analytical expressions pertaining to the concentrations of cell density, repressor proteins, pump expressions, intracellu- lar biofuel and extracellular biofuel are presented. The constant pump model is compared with feedback loop model analytically to know the biofuel production. The numerical solution of this problem is also reported using Scilab/Matlab program. Also, the analytical results are compared with previous published numerical results and found to be in good agreement.
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Low threshold polariton lasing in a highly disordered conjugated polymer

Low threshold polariton lasing in a highly disordered conjugated polymer

24 μ m in diameter. Emission from the microcavities was colli- mated by the objective and then split into two paths in a home-built Michelson interferometer with a non-polarizing cube beam-splitter. The Michelson interferometer included in a hollow retroreflector, used to invert the emission spot before interfering with the reference beam on the spectrometer CCD. A pair of color filters were used to block transmitted UV and residual infra- red light from the excitation beam. All measurements were carried out at room temperature in air, but an external optical shutter was synchronized with the signal acquisition process of the spectrom- eter to reduce unnecessary photo-oxidation by the pump laser. C. Fringe Visibility Contrast Fitting
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Autonomous Greenhouse using Internet of Things with Thingspeak

Autonomous Greenhouse using Internet of Things with Thingspeak

In Field3 chart the soil moisture values are varied. The variation is in the form of increasing and decreasing and stable sometime. So whenever the humidity value greater less than or equal to the threshold value the water pump switched on automatically. In the same way Felid4 chart visualized in the thingspeak. The light will be on and off according to the LDR sensor module threshold value condition.

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 A REVIEW ON OSMOTIC DRUG DELIVERY SYSTEM

 A REVIEW ON OSMOTIC DRUG DELIVERY SYSTEM

Conventional oral drug delivery systems supply an instantaneous release of drug, which cannot control the release of the drug and effective concentration at the target site. This kind of dosing pattern may result in constantly changing, unpredictable plasma concentrations. Drugs can be delivered in a controlled pattern over a long period of time by the process of osmosis. Osmotic devices are the most promising strategy based systems for controlled drug delivery. They are the most reliable controlled drug delivery systems and could be employed as oral drug delivery systems. Various patents available for osmotic drug delivery system like Rose-Nelson pump, Higuchi leeper pump, Higuchi Theeuwes pump, Elementary Osmotic pump etc. ODDS are useful for poorly soluble drug, for pulsatile drug release, zero order release. Various techniques available for preparation of ODDS include push pull osmotic Pump, osmotic Brusting osmotic pump, liquid oral osmotic system, sandwiched osmotic tablets , delayed delivery osmotic device, monolithic osmotic System and controlled porosity osmotic Pump. Osmotically controlled oral drug delivery systems utilize osmotic pressure for controlled delivery of active agents. These systems can be utilized for systemic as well as targeted delivery of drugs. The release of drugs from osmotic systems is governed by various formulation factors such as solubility and osmotic pressure of the core components, size of the delivery orifice, and nature of the rate-controlling membrane. In this Paper mainly focused on the Osmotic System with example, the basic component of osmotic system and evaluation parameter of the osmotic drug delivery system.
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Quantum optics of multi-level lasers

Quantum optics of multi-level lasers

Taking the case of 2x threshold we find (Or = 420 kHz in good agreem ent with Fig.5 .10(a). From Eq.5.16 we see we can improve the situation for squeezing by increasing the scaled dipole coupling constant, thus pushing the RRO to higher frequencies at the same pump rates. Alternatively we can reduce the cavity decay rate such that the RRO no longer falls within the cavity linewidth. The disadvantage with decreasing the cavity linewidth is that it can becomes comparable with the frequency at which you wish to observe the squeezing. In Fig.5.11 we show the effect of increasing the scaled dipole coupling strength of the laser medium for pump powers 5x (Fig.5.11 (a)) and lOx (Fig.5.11 (b)) above threshold. The frequency at which squeezing can be observed is significantly increased in both cases. However spontaneous emission noise still limits the squeezing this close to threshold (see 5.2.2). For a particular atomic system the scaled dipole coupling strength can be increased by increasing the density of active atoms. However the density of atoms is limited by the desire to avoid inter-atomic effects.
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Relaxed damage threshold intensity conditions and nonlinear increase in the conversion efficiency of an optical parametric oscillator using a bi-directional pump geometry

Relaxed damage threshold intensity conditions and nonlinear increase in the conversion efficiency of an optical parametric oscillator using a bi-directional pump geometry

We address this limitation by employing a novel bi-directional pump geometry for a singly resonant synchronously pumped ultra-short pulsed OPO. Instead of employing a conventional single-pass geometry, by simultaneously synchronizing a „forward‟ pump pulse and a second counter-propagating pulse in the „reverse‟ direction together with the circulating signal pulse, the signal electric field amplitude experiences gain in both directions and hence the resulting average output power scales nonlinearly with the overall input pump power. By ensuring only one pump pulse with an intensity level below the damage threshold intensity is present in the nonlinear crystal at any given time, this technique permits a total pump intensity of up to twice the damage threshold intensity, without incurring damage. As a consequence, the crystal damage threshold intensity conditions can be relaxed and the average and peak output powers of the OPO can be significantly increased
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Threshold Effects of Inflation on Economic Growth: Evidence from Dynamic Panel Threshold Regression Analysis for 18 Developed Economies

Threshold Effects of Inflation on Economic Growth: Evidence from Dynamic Panel Threshold Regression Analysis for 18 Developed Economies

Bick (2010) applied non-dynamic (static) panel threshold regression that propounded by Hansen (1999) on a balanced panel data from 40 developing countries. He managed to find a threshold inflation of 19.16% with no regime intercepts and 12.03% by allowing regime intercepts. Their study included the regime intercept which manages to unfold the effects of the threshold. More recent studies by Ibarra and Trupkin (2011), using Panel Smooth Transition Regression (PSTR) that propounded by Gonzalez et al. (2005) obtain a threshold inflation of 4.1% and 19.1% for industrial and non-industrial countries respectively. Same results share by Seleteng et al. (2013), also using PSTR on the Southern African Development Community (SADC) region. Their threshold inflation is at 18.9%. Both Ibarra and Trupkin (2011) and Seleteng et al. (2013) have the impact of inflation is negative on growth in both inflation regimes, but only statistically significant when inflation is above the threshold (high inflation-regime).
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Effect of Diet Viscosity on the Operation of the Pharyngeal Pump in the Blood Feeding Bug Rhodnius Prolixus

Effect of Diet Viscosity on the Operation of the Pharyngeal Pump in the Blood Feeding Bug Rhodnius Prolixus

If the pump rhythm depends on a central oscillator, then increasing the viscosity should not affect the pump frequency; assuming the pressure produced by the pump cannot increase substan[r]

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“Analysis For Operating Cost Of Split Case Pump For Its Life Cycle”

“Analysis For Operating Cost Of Split Case Pump For Its Life Cycle”

Abstract— Pumping systems for all services consume an estimated one-fifth of all electricity produced. With the changing industrial scenario, customers are now focusing on energy cost and maintenance cost of the product apart from initial investment cost. Earth’s resources are finite and also there is a growing concern that the use of energy can contribute directly or indirectly to environmental pollution. KBL as one of the leading pump manufacturer have shown prime responsibility to implement this technology in order to contribute energy conservation. KBL has used this concept effectively in products and introduced in market.
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Auxiliary Power Saving In Air Cooled Steam Condenser by Pumps   (A Heat Exchanger Used In Steam Power Plant)

Auxiliary Power Saving In Air Cooled Steam Condenser by Pumps (A Heat Exchanger Used In Steam Power Plant)

Cavitation or vaporization is the formation of bubbles inside the pump. This may occur when at the fluid’s local static pressure becomes lower than the liquid’s vapor pressure (at the actual temperature). A possible cause is when the fluid accelerates in a control valve or around a pump impeller. Vaporization itself does not cause any damage. However, when the velocity is decreased and pressure increased, the vapor will evaporate and collapse.

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DUPLEX 120 VOLT FLOAT CONTROL PANEL STANDARD SPECIFICATION

DUPLEX 120 VOLT FLOAT CONTROL PANEL STANDARD SPECIFICATION

Seals Failure relays providing adjustable resistance sensing circuitry from 0 to 250,000 ohms for each pump shall be supplied. Upon activation, the seal failure relay shall not shut down the pump but shall illuminate a red pilot light located on the inner door that shall correspond to the appropriate pump. The moisture sensing probes shall be supplied and installed in the pumps by the pump manufacturer.

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[R445.Ebook] Download PDF Pump Characteristics And Applications Third Edition Mechanical Engineering By Michael Volk.pdf

[R445.Ebook] Download PDF Pump Characteristics And Applications Third Edition Mechanical Engineering By Michael Volk.pdf

Pump Characteristics and Applications, Third Edition is appropriate for readers with all levels of technical experience, including engineering and pump industry professionals, pump operators and maintenance technicians, upper-level undergraduate and graduate students in mechanical engineering, and students in engineering technology programs.

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