Clinical and Radiological Comparison of Posterolateral Fusion and Posterior Interbody Fusion Techniques for Multilevel Lumbar Spinal Stabilization In Manual Workers

Hayati Aygün,Albert Çakar,Nergiz Hüseyinoğlu,Urfettin Hüseyinoğlu,Recep Çelik 대한척추외과학회 2014 Asian Spine Journal Vol.8 No.5

Study Design: Eighty-four patients who had been treated for degenerative spinal diseases between January 2006 and June 2009 were reviewed retrospectively. Purpose: We aimed to compare the clinical and radiologic findings of manual workers who underwent posterolateral fusion (PLF) or posterior interbody fusion (PLIF) involving fusion of 3 or more levels of the spine. Overview of Literature: Previous studies have concluded that there is no significant difference between the clinical outcome of PLF and PLIF techniques. Methods: After standard decompression, 42 patients underwent PLF and the other 42 patients underwent PLIF. Radiologic findings, Oswestry disability index (ODI) scores, and visual analogue scale (VAS) scores were assessed preoperatively and at 6-month intervals postoperatively and return to work times/rates were assessed for 48 months. Results: Patients who underwent PLF had significantly shorter surgical time and less blood loss. According to the 48-month clinical results, ODI and VAS scores were reduced significantly in the two groups, but the PLIF group showed better results than the PLF group at the last follow-up. Return to work rate was 63% in the PLF group and 87% in the PLIF group. Union rates were found to be 81% and 89%, respectively, after 24 months (p =0.154). Conclusions: PLIF is a preferable technique with respect to stability and correction, but the result does not depend on only the fusion rates. Discectomy and fusion mass localization should be considered for achieving clinical success with the fusion technique. Before performing PLIF, the association of the long operative time and high blood loss with mortality and morbidity should be taken into consideration, particularly in the elderly and disabled patients.

An optimal discrete-time feedforward compensator for real-time hybrid simulation

Hayati, Saeid,Song, Wei Techno-Press 2017 Smart Structures and Systems, An International Jou Vol.20 No.4

Real-Time Hybrid Simulation (RTHS) is a powerful and cost-effective dynamic experimental technique. To implement a stable and accurate RTHS, time delay present in the experiment loop needs to be compensated. This delay is mostly introduced by servo-hydraulic actuator dynamics and can be reduced by applying appropriate compensators. Existing compensators have demonstrated effective performance in achieving good tracking performance. Most of them have been focused on their application in cases where the structure under investigation is subjected to inputs with relatively low frequency bandwidth such as earthquake excitations. To advance RTHS as an attractive technique for other engineering applications with broader excitation frequency, a discrete-time feedforward compensator is developed herein via various optimization techniques to enhance the performance of RTHS. The proposed compensator is unique as a discrete-time, model-based feedforward compensator. The feedforward control is chosen because it can substantially improve the reference tracking performance and speed when the plant dynamics is well-understood and modeled. The discrete-time formulation enables the use of inherently stable digital filters for compensator development, and avoids the error induced by continuous-time to discrete-time conversion during the compensator implementation in digital computer. This paper discusses the technical challenges in designing a discrete-time compensator, and proposes several optimal solutions to resolve these challenges. The effectiveness of compensators obtained via these optimal solutions is demonstrated through both numerical and experimental studies. Then, the proposed compensators have been successfully applied to RTHS tests. By comparing these results to results obtained using several existing feedforward compensators, the proposed compensator demonstrates superior performance in both time delay and Root-Mean-Square (RMS) error.

Comprehensive Evaluation of Fast-Response, Reynolds-Averaged Navier-Stokes, and Large-Eddy Simulation Methods Against High-Spatial-Resolution Wind-Tunnel Data in Step-Down Street Canyons

Hayati, Arash Nemati,Stoll, Rob,Kim, J. J.,Harman, Todd,Nelson, Matthew A.,Brown, Michael J.,Pardyjak, Eric R. Springer-Verlag 2017 Boundary-layer meteorology Vol.164 No.2

<P>Three computational fluid dynamics (CFD) methods with different levels of flow-physics modelling are comprehensively evaluated against high-spatial-resolution wind-tunnel velocity data from step-down street canyons (i.e., a short building downwind of a tall building). The first method is a semi-empirical fast-response approach using the Quick Urban Industrial Complex (QUIC-URB) model. The second method solves the Reynolds-averaged Navier-Stokes (RANS) equations, and the third one utilizes a fully-coupled fluid-structure interaction large-eddy simulation (LES) model with a grid-turbulence inflow generator. Unlike typical point-by-point evaluation comparisons, here the entire two-dimensional wind-tunnel dataset is used to evaluate the dynamics of dominant flow topological features in the street canyon. Each CFD method is scrutinized for several geometric configurations by varying the downwind-to-upwind building-height ratio () and street canyon-width to building-width aspect ratio (S / W) for inflow winds perpendicular to the upwind building front face. Disparities between the numerical results and experimental data are quantified in terms of their ability to capture flow topological features for different geometric configurations. Overall, all three methods qualitatively predict the primary flow topological features, including a saddle point and a primary vortex. However, the secondary flow topological features, namely an in-canyon separation point and secondary vortices, are only well represented by the LES method despite its failure for taller downwind building cases. Misrepresentation of flow-regime transitions, exaggeration of the coherence of recirculation zones and wake fields, and overestimation of downwards vertical velocity into the canyon are the main defects in QUIC-URB, RANS and LES results, respectively. All three methods underestimate the updrafts and, surprisingly, QUIC-URB outperforms RANS for the streamwise velocity component, while RANS is superior to QUIC-URB for the vertical velocity component in the street canyon.</P>

Synthesis and Characterization of Gold Nanostars with Different Method

( Sabrina Hayati ),이혜진 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

Gold nanparticles receive particular interest due to their unique properties and application. The shape and crystallographic facets are the major factors in determining the catalytic and surface activity of metal nanoparticles and the size can influence the optical properties of metal nanoparticles. This work investigates gold nanoparticles star-shaped synthesis with two different method; surfactant-capped and free-surfactant synthesis to increase yield, homogeneous distribution, and small size of nanostars. High-yield and monodispersity of nanostars obtain from free-surfactant synthesis method. The small core size of nanostars and multiple long thin branches also presented by this method.

Microstrip Lowpass Filter with Very Sharp Transition Band and Wide Stopband

Mohsen Hayati,Akram Sheikhi 한국전자통신연구원 2011 ETRI Journal Vol.33 No.6

A novel lowpass filter with a very sharp transition band and wide stopband is proposed. The proposed filter is based on T-shaped patches which are etched in symmetrical structures and folded open stub. To obtain a wide stopband, we have used stub loaded semi-circle stepped-impedance structures. By designing the resonator with high inductance and capacitance, a very sharp transition band is achieved. The proposed filter has a 3-dB cutoff frequency at 2.37 GHz and a 40-dB rejection at 2.44 GHz. The stopband with an attenuation level better than −13.2 dB is up from 2.4 GHz to 16 GHz, and consequently we have reached the high and wide rejection in stopband with compact size. Good agreements between the simulated and the measured results are presented.

Microstrip Lowpass Filter with Very SharpTransition Band Using T-Shaped, Patch, and Stepped Impedance Resonators

Mohsen Hayati,Akram Sheikhi 한국전자통신연구원 2013 ETRI Journal Vol.35 No.3

A compact microstrip lowpass filter (LPF) with an elliptic function response is proposed. A high equivalent capacitance and inductance between the structures of the resonator result in the sharp transition band of 0.04 GHz from 4 GHz to 4.04 GHz with an attenuation level of –3 dB and –20 dB, respectively. To improve the LPF rejection band, multiple open stubs are connected to the proposed resonator. A filter with a 3-dB cut-off frequency at 4 GHz is designed, fabricated, and measured, and agreement between the measured and simulated results is achieved. The results show that a stopband bandwidth of 131% with a suppression level better than –20 dB is obtained while achieving a compact size with a wide stopband.

Double Gate MOSFET Modeling Based on Adaptive Neuro-Fuzzy Inference System for Nanoscale Circuit Simulation

Mohsen Hayati,Majid Seifi,Abbas Rezaei 한국전자통신연구원 2010 ETRI Journal Vol.32 No.4

As the conventional silicon metal-oxide-semiconductor field-effect transistor (MOSFET) approaches its scaling limits, quantum mechanical effects are expected to become more and more important. Accurate quantum transport simulators are required to explore the essential device physics as a design aid. However, because of the complexity of the analysis, it has been necessary to simulate the quantum mechanical model with high speed and accuracy. In this paper, the modeling of double gate MOSFET based on an adaptive neuro-fuzzy inference system (ANFIS) is presented. The ANFIS model reduces the computational time while keeping the accuracy of physics-based models, like non-equilibrium Green’s function formalism. Finally, we import the ANFIS model into the circuit simulator software as a subcircuit. The results show that the compact model based on ANFIS is an efficient tool for the simulation of nanoscale circuits.

Design and Optimization of Full Comparator Based on Quantum-Dot Cellular Automata

Mohsen Hayati,Abbas Rezaei 한국전자통신연구원 2012 ETRI Journal Vol.34 No.2

Quantum-dot cellular automata (QCA) is one of the few alternative computing platforms that has the potential to be a promising technology because of higher speed, smaller size, and lower power consumption in comparison with CMOS technology. This letter proposes an optimized full comparator for implementation in QCA. The proposed design is compared with previous works in terms of complexity, area, and delay. In comparison with the best previous full comparator, our design has 64% and 85% improvement in cell count and area, respectively. Also, it is implemented with only one clock cycle. The obtained results show that our full comparator is more efficient in terms of cell count, complexity, area, and delay compared to the previous designs. Therefore, this structure can be simply used in designing QCA-based circuits.

The effects of limestone powder and fly ash as an addition on fresh, elastic, inelastic and strength properties of self-compacting concrete

Hilmioglu, Hayati,Sengul, Cengiz,Ozkul, M. Hulusi Techno-Press 2022 Advances in concrete construction Vol.14 No.2

In this study, limestone powder (LS) and fly ash (FA) were used as powder materials in self-compacting concrete (SCC) in increasing quantities in addition to cement, so that the two powders commonly used in the production of SCC could be compared in the same study. Considering the reduction of the maximum aggregate size in SCC, 10 mm or 16 mm was selected as the coarse aggregate size. The properties of fresh concrete were determined by slump flow (including T₅₀₀ time), V-funnel and J-ring experiments. The experimental results showed that as the amount of both LS and FA increased, the slump flow also increased. The increase in powder material had a negative effect on V-funnel flow times, causing it to increase; however, the increase in FA concretes was smaller compared to LS ones. The increase in the powder content reduced the amount of blockage in the J-ring test for both aggregate sizes. As the hardened concrete properties, the compressive and splitting strengths as well as the modulus of elasticity were determined. Longitudinal and transverse deformations were measured by attaching a special frame to the cylindrical specimens and the values of Poisson's ratio, initiation and critical stresses were obtained. Despite having a similar W/C ratio, all SCC exhibited higher compressive strength than NVC. Compressive strength increased with increasing powder content for both LS and FA; however, the increase of the FA was higher than the LS due to the pozzolanic effect. SCC with a coarse aggregate size of 16 mm showed higher strength than 10 mm for both powders. Similarly, the modulus of elasticity increased with the amount of powder material. Inelastic properties, which are rarely found in the literature for SCC, were determined by measuring the initial and critical stresses. Crack formation in SCC begins under lower stresses (corresponding to lower initial stresses) than in normal concretes, while critical stresses indicate a more brittle behavior by taking higher values.

Does Clinical Experience Help Oncology Nursing Staff to Deal with Patient Pain Better than Nurses from other Displines? Knowledge and Attitudes Survey Amongst Nurses in a Tertiary Care in Malaysia

Yaakup, Hayati,Eng, Tan Chai,Shah, Shamsul Azhar Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.12

Background: Successful implementation of pain management procedures and guidelines in an institution depends very much on the acceptance of many levels of healthcare providers. Aim: The main purpose of this study was to determine the level of knowledge and attitudes regarding pain among nurses working in tertiary care in a local setting and the factors that may be associated with this. Materials and Methods: This cross-sectional research study used a modified version of the Nurses' Knowledge and Attitudes Survey (NKAS) regarding pain. Basic demographic data were obtained for further correlation with the level of pain knowledge. Results: A total of 566 nurses, 34 male and 532 female, volunteered to participate in this study. The response rate (RR) was 76%, with an overall mean percentage score of $42.7{\pm}10.9$ (range: 5-92.5). The majority of participants were younger nurses below 40 years of age and more than 70% had worked for less than 10 years ($6.6{\pm}4.45$). Up to 92% had never had any formal education in pain management in general. The total mean score of correct answers was $58.6{\pm}9.58$, with oncology nursing staff scoring a higher percentage when compared with nurses from other general and critical care wards ($63.52{\pm}9.27$, p<0.045). Only 2.5% out of all participants obtained a score of 80% or greater. The majority of the oncology nurses achieved the expected competency level (p<0.03). Conclusions: The present findings give further support for the universal concern about poor knowledge and attitudes among nurses' related to the optimal management of pain. The results reflected that neither number of years working nor age influenced the level of knowledge or attitudes of the practising nurses. Oncology nursing staff consistently scored better than the rest of the cohort. This reflects that clinical experience helped to improve attitudes and knowledge concerning better pain management.