Engineering Commons^™

Upscaling Wetland Methane Emissions From The Fluxnet-Ch4 Eddy Covariance Network (Upch4 V1.0): Model Development, Network Assessment, And Budget Comparison, Gavin Mcnicol, Etienne Fluet-Chouinard, Zutao Ouyang, Sara Knox, Zhen Zhang, Tuula Aalto, Sheel Bansal, Kuang Yu Chang, Min Chen, Kyle Delwiche, Sarah Feron, Mathias Goeckede, Jinxun Liu, Avni Malhotra, Joe R. Melton, William Riley, Rodrigo Vargas, Kunxiaojia Yuan, Qing Ying, Qing Zhu, Pavel Alekseychik, Mika Aurela, David Billesbach, David I. Campbell, Jiquan Chen, Housen Chu, Ankur R. Desai, Eugenie Euskirchen, Jordan Goodrich, Timothy Griffis, Manuel Helbig, Takashi Hirano, Hiroki Iwata, Gerald Jurasinski, John King, Franziska Koebsch, Randall Kolka, Ken Krauss, Annalea Lohila, Ivan Mammarella

Department of Biological Systems Engineering: Papers and Publications

Wetlands are responsible for 20%–31% of global methane (CH4) emissions and account for a large source of uncertainty in the global CH4 budget. Data-driven upscaling of CH4 fluxes from eddy covariance measurements can provide new and independent bottom-up estimates of wetland CH4 emissions. Here, we develop a six-predictor random forest upscaling model (UpCH4), trained on 119 site-years of eddy covariance CH4 flux data from 43 freshwater wetland sites in the FLUXNET-CH4 Community Product. Network patterns in site-level annual means and mean seasonal cycles of CH4 fluxes were reproduced accurately in tundra, boreal, and temperate regions (Nash-Sutcliffe Efficiency ∼0.52–0.63 and 0.53). …

Altered Skeletal Muscle Excitation-Contraction Coupling In The R6/2 Transgenic Mouse Model For Huntington's Disease, Daniel R. Miranda

Browse all Theses and Dissertations

Huntington’s disease (HD) has classically been categorized as a neurodegenerative disorder. However, the expression of the disease-causing mutated huntingtin gene in skeletal muscle may contribute to the symptoms of HD, namely those that involve involuntary muscle contraction. In the R6/2 transgenic mouse model of HD, we previously observed ion channel defects that could contribute to involuntary muscle contraction. Here, in R6/2 muscle we investigated the consequence of these ion channel defects on action potentials (APs), the first step in excitation-contraction (EC) coupling. We found that the ion channel defects were associated with depolarizing the baseline membrane potential during AP trains. …

Altered Skeletal Muscle Excitation-Contraction Coupling In The R6/2 Transgenic Mouse Model For Huntington's Disease, Daniel R. Miranda

Browse all Theses and Dissertations

Huntington’s disease (HD) has classically been categorized as a neurodegenerative disorder. However, the expression of the disease-causing mutated huntingtin gene in skeletal muscle may contribute to the symptoms of HD, namely those that involve involuntary muscle contraction. In the R6/2 transgenic mouse model of HD, we previously observed ion channel defects that could contribute to involuntary muscle contraction. Here, in R6/2 muscle we investigated the consequence of these ion channel defects on action potentials (APs), the first step in excitation-contraction (EC) coupling. We found that the ion channel defects were associated with depolarizing the baseline membrane potential during AP trains. …

Design, Discovery, And Characterization Of Single Crystals Of A Topological Semimetal Using A Self-Flux Method, Sudha Krishnan

MSU Graduate Theses

Realization of topological semimetals in the recent past show that ternary intermetallics can exhibit topological phases. This discovery initiated the quest for this novel research. There is a crucial need to discover new materials that manifest these phases for a better understanding of their behavior to utilize them in device technology. Also, Bi compounds have attracted much attention as candidates for topological materials and topological superconductors. In this context, synthesis and characterization of single crystals of a layered transition metal pnictide SmMnBi2, a potential Dirac topological semimetal candidate, is reported. A flux method was utilized to synthesize single crystals of …

Propuesta Preliminar De Diseño Para Un Sistema De Separación De Proteínas Del Lactosuero Usando Ultrafiltración, Natalia Monroy Pedraza

Ingeniería de Alimentos

El lactosuero es un subproducto de la elaboración de quesos, tradicionalmente es usado para alimentación animal y en muchos casos es desechado como efluente, generando un gran impacto ambiental, este cuenta aproximadamente con el 55% de los nutrientes de la leche. Dependiendo del tipo de queso se obtienen diferentes tipos de lactosuero, estos varían en su composición, sin embargo, en todos los casos la lactosa es su componente mayoritario seguido de las proteínas, siendo estas de gran valor biológico. En este trabajo se evaluó experimentalmente la separación de las proteínas contenidas en el lactosuero usando membranas de ultrafiltración, analizando la …

A Study And Simulation Of Flux Induced Corrosion In Copper Tubing Used For The Distribution Of Potable Water, Daniel O. Benham

Materials Engineering

Water side corrosion within copper plumbing can occur due to a wide variety of unwanted circumstances. Through the controlled immersion of six ¾” copper tubing samples with five utilizing a unique industry standard soldering flux, this investigation associates residual flux deposits with the initiation of pitting in copper. Water stagnation in a copper potable water distribution system, typically associated with an infrequently used faucet, is a condition highly prone to copper pitting. A test apparatus designed to produce a partially stagnant flow condition with scheduled electrolyte flushes every 3 days was developed and constructed to contain 6 test samples for …

Optimization Of Analytical Inverse Heat Transfer Recovery Solution, Nathan Schick

Masters Theses

This thesis describes the different methods used when trying to solve inverse heat transfer problems, particularly those involving recovering heat flux. There are currently several techniques to measure the temperature history in an object subjected to heat transfer using various temperature sensors, however these types of sensors are gradually being replaced by Temperature Sensitive Paints (TSP), a technique that is more accurate and provides a better spatial resolution. TSP is a polymer that is applied on a base object. Changes in temperature in the polymer result in variations of the luminescence intensity in the paint. These variations can be captured …

Water Chemistry Dynamics In Four Vernal Pools In Maine, Usa, Lydia H. Kifner

Electronic Theses and Dissertations

Vernal pools are small seasonal wetlands that are a common landscape feature that contribute to biodiversity in northeastern North American forests. However, even basic information about their biogeochemical functions, such as carbon cycling, is limited. Dissolved gas concentrations (CH₄, CO₂) and other water chemistry parameters were monitored weekly at the bottom and surface of four vernal pools in central and eastern Maine, USA, from April to August 2016. The vernal pools were supersaturated with respect to CH₄ and CO₂ at all sampling dates and locations. Concentrations of dissolved CH₄ and CO₂ ranged …

Revelation Of Yin-Yang Balance In Microbial Cell Factories By Data Mining, Flux Modeling, And Metabolic Engineering, Gang Wu

McKelvey School of Engineering Theses & Dissertations

The long-held assumption of never-ending rapid growth in biotechnology and especially in synthetic biology has been recently questioned, due to lack of substantial return of investment. One of the main reasons for failures in synthetic biology and metabolic engineering is the metabolic burdens that result in resource losses. Metabolic burden is defined as the portion of a host cells resources either energy molecules (e.g., NADH, NADPH and ATP) or carbon building blocks (e.g., amino acids) that is used to maintain the engineered components (e.g., pathways). As a result, the effectiveness of synthetic biology tools heavily dependents on cell capability to …

Study Of Flux Pinning Mechanism Under Hydrostatic Pressure In Optimally Doped (Ba,K)Fe2as2 Single Crystals, Babar Shabbir, Xiaolin Wang, Yanwei Ma, S X. Dou, Shi-Shen Yan, Liang-Mo Mei

Australian Institute for Innovative Materials - Papers

Strong pinning depends on the pinning force strength and number density of effective defects. Using the hydrostatic pressure method, we demonstrate here that hydrostatic pressure of 1.2 GPa can significantly enhance flux pinning or the critical current density (Jc) of optimally doped Ba0.6K0.4Fe2As2 crystals by a factor of up to 5 in both low and high fields, which is generally rare with other Jc enhancement techniques. At 4.1 K, high pressure can significantly enhance Jc from 5 x 105 A/cm2 to nearly 106 A/cm2 at 2 T, and from 2 x 105 A/cm2 to nearly 5.5 x 105 A/cm2 at …

Ray Optics Behavior Of Flux Avalanche Propagation In Superconducting Films, Pavlo Mikheenko, Tom H. Johansen, Supratim Chaudhuri, I J. Maasilta, Y Galperin

Australian Institute for Innovative Materials - Papers

Experimental evidence of wave properties of dendritic flux avalanches in superconducting films is reported. Using magneto-optical imaging the propagation of dendrites across boundaries between a bare NbN film and areas coated by a Cu layer was visualized, and it was found that the propagation is refracted in full quantitative agreement with Snell's law. For the studied film of 170 nm thickness and a 0.9μm thick metal layer, the refractive index was close to n=1.4. The origin of the refraction is believed to be caused by the dendrites propagating as an electromagnetic shock wave, similar to damped modes …

Mercury Transport And Fluxes In The Lake Ontario Basin, Joseph Steven Denkenberger

Dissertations - ALL

In this dissertation I assess mercury dynamics in the Lake Ontario Basin. In four interrelated phases, ecosystem mercury concentrations and fluxes were analyzed at increasing scales. Each phase is presented in order of increasing scale, starting with a reach-by-reach analysis in the Seneca River in New York, then moving up to an analysis of the Lake Ontario watershed, followed by an assessment of Lake Ontario, and culminating with an estimate of atmospheric mercury exchange for the entire Great Lakes Basin.

Phase 1 of my research is a multi-year study exploring mercury (Hg) dynamics in the Three Rivers system, with particular …

Flux Pinning Mechanism In Bafe1.9ni0.1as2 Single Crystals: Evidence For Fluctuation In Mean Free Path Induced Pinning, M Shahbazi-Manshadi, X L Wang, K Y Choi, S X. Dou

Shi Xue Dou

The flux pinning mechanism of BaFe1.9Ni0.1As2 superconducting crystals have been investigated systematically by magnetic measurements up to 13 T at various temperatures. The field dependence of the critical current density, Jc, was analysed within the collective pinning model. A remarkably good agreement between the experimental results and theoretical dl pinning curve is obtained, which indicates that pinning in BaFe1.9Ni0.1As2 crystal originates from spatial variation of the mean free path. Moreover, the normalized pinning force density, Fp, curves versus h1/4B/Birr (Birr is the irreversibility field) were scaled using the Dew-Hughes model. Analysis suggests that point pinning alone cannot explain the observed …

The Flux Pinning Mechanism, And Electrical And Magnetic Anisotropy In Fe1.04te0.6se0.4 Superconducting Single Crystal, Mahboobeh Shahbazi-Manshadi, Xiaolin Wang, S X. Dou, H Fang, C T. Lin

Shi Xue Dou

The temperature and magnetic field dependences of the magnetization and critical current density of Fe1.04Te0.6Se0.4 single crystals have been investigated, and the flux pinning mechanism has been analysed. The normalized pinning force (fp Fp/F p,max) vs. h(H/Hirr) curves, are scaled using the Dew-Hughes theory, f(h) ≈ hp(1 - h)q with p 1.35 and q 3.06. The angular dependence of the resistivity under different magnetic fields shows a dip-like structure, below the superconducting transition temperature. The anisotropic value of 2 was obtained using Ginzburg-Landau theory.

Impact Of Organic And Colloidal Fouling On Trace Organic Contaminant Rejection By Forward Osmosis: Role Of Initial Permeate Flux, Ming Xie, Long D. Nghiem, William E. Price, Menachem Elimelech

Faculty of Engineering and Information Sciences - Papers: Part A

Fouling behaviour and its impact on the rejection of trace organic contaminants (TrOCs) by forward osmosis (FO) were investigated.Membrane fouling was simulated using humic acid and colloidal particles asmodel foulants at different initial permeatewater fluxes.Water flux declinewas insignificant at an initial permeate flux of 9 L/m2h and the fouling layerwas loose and fluid-like. By contrast, thewater flux declinewas substantial at an initial permeate flux of 20 L/m2h, resulting in the formation of a compact fouling layer. Water flux recovery after physical cleaning for both humic acid and colloidal particle fouledmembraneswas consistently higher at an initial permeate flux of 9 L/m2h …

Effects Of Chemical Preservation On Flux And Solute Rejection By Reverse Osmosis Membranes, Kha L. Tu, Allan Chivas, Long D. Nghiem

Faculty of Engineering and Information Sciences - Papers: Part A

This study investigates the impacts of chemical preservation on the performance of polyamide reverse osmosis membranes with respect to water permeability and solute rejection. Three preservative chemicals, namely formaldehyde, sodium metabisulfite, and 2,2-Dibromo-3-Nitrilopropionamide, were evaluated for membrane preservation at pH 3 and 7. Experimental data show that chemical preservation may change the membrane surface properties, and consequently water permeability and solute rejection efficiency of the membrane are negatively impacted. The impacts of preservation on boron rejection and sodium rejection are similar in magnitude and more significant than those on water permeability. The results indicate that the impact of chemical preservation …

Design Of A Double-Stator Linear Switched Reluctance Motor For Shunting Railway Channels, El Manaa Barhoumi, Mansour Hajji, Boujemaa Ben Salah

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the design and modeling of a double-stator linear switched reluctance motor for motorizing a railway channels' shunting system. The magnetic behavior of this actuator is nonlinear due to the saturation and nonlinear magnetization curves of the materials used in this actuator. For this reason, the electromagnetic quantities such as force, flux linkage, and inductance are calculated with the finite element method using the Maxwell tool. The obtained results are presented and discussed. In order to elaborate some control strategies, a new model for the proposed actuator, based on the flux and force characteristics, is validated by the …

Controllable Morphology Of Flux Avalanches In Microstructured Superconductors, M Motta, F Colauto, J I. Vestgarden, Joachim Fritzsche, M Timmermans, J Cuppens, C Attanasio, C Cirillo, V V. Moshchalkov, J Van De Vondel, Tom H. Johansen, W A. Ortiz, A V. Silhanek

Australian Institute for Innovative Materials - Papers

The morphology of abrupt bursts of magnetic flux into superconducting films with engineered periodic pinning centers (antidots) has been investigated. Guided flux avalanches of thermomagnetic origin develop a treelike structure, with the main trunk perpendicular to the borders of the sample, while secondary branches follow well-defined directions determined by the geometrical details of the underlying periodic pinning landscape. Strikingly, we demonstrate that in a superconductor with relatively weak random pinning the morphology of such flux avalanches can be fully controlled by proper combinations of lattice symmetry and antidot geometry. Moreover, the resulting flux patterns can be reproduced, to the finest …

Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic

Josip Horvat

We have systematically studied the flux pinning behavior of MgB2 bulks synthesized by direct diffusion of Mg into pressed pellets of high purity crystalline B powder, with and without mixing with C and SiC nanoparticles, at a reaction temperature of 850degC for 10 hrs. All of the samples showed very high purity and high density, but their microstructure and flux pinning behavior showed significant differences. It was found that the pure MgB2 agrees with the deltaTc pinning model, nano-C doped MgB2 agrees with the deltal pinning model, while the SiC+MgB2 composite agrees with the deltaepsiv pinning model (stress/strain field pinning), …

Flux Dynamics In (Y, Nd)1ba2cu3o7 Superconductors, A S Mahmoud, Josip Horvat, S X. Dou

Josip Horvat

The vortex dynamics of (Y, Nd)Ba2Cu3O7−δ ((Y, Nd)123) superconductors have been studied using magnetic relaxation measurements obtained at different sweep rates. The temperature dependence of the dynamic relaxation rate (Q) is found to be not vanishing at T = 0 K, and also showed well developed maxima becoming broader and tending to move to higher temperatures with decreasing magnetic field. At temperatures close to the critical temperature (T c ), Q(T) showed well-developed minima becoming deeper and tending to move to lower temperatures with increasing field. These minima appeared to occur approximately at the same reduced temperature position [ T/T …

Performance Of A Novel Osmotic Membrane Bioreactor (Ombr) System: Flux Stability And Removal Of Trace Organics, Abdulhakeem Alturki, James Mcdonald, Stuart J. Khan, Faisal I. Hai, William E. Price, Long Nghiem

Faisal I Hai

Results reported here highlight the potential and several challenges in the development of a novel osmotic membrane bioreactor (OMBR) process for the treatment of municipal wastewater. Following the initial gradual decline, a stable permeate flux value was obtained after approximately four days of continuous operation. There was evidence of continuous deterioration of biological activity of the OMBR system, possibly due to the build-up of salinity in the reactor. The removal of 25 out of 27 trace organic compounds with molecular weight higher than 266 g/mol was above 80% and was possibly governed by the interplay between physical separation of the …

Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic

Jianli Wang

We have systematically studied the flux pinning behavior of MgB2 bulks synthesized by direct diffusion of Mg into pressed pellets of high purity crystalline B powder, with and without mixing with C and SiC nanoparticles, at a reaction temperature of 850degC for 10 hrs. All of the samples showed very high purity and high density, but their microstructure and flux pinning behavior showed significant differences. It was found that the pure MgB2 agrees with the deltaTc pinning model, nano-C doped MgB2 agrees with the deltal pinning model, while the SiC+MgB2 composite agrees with the deltaepsiv pinning model (stress/strain field pinning), …

Flux Distribution In Fe-Based Superconducting Materials By Magneto-Optical Imaging, Zhi Wei Lin, Jian Guo Zhu, You Guang Guo, Xiaolin Wang, S X. Dou, Tom H. Johansen, Xun Shi, K Y. Choi

Shi Xue Dou

"This paper presents the magnetic flux distributions in Fe-based superconducting materials including single crystal of Ba(Fe1.9Ni0.1)As2 and Ba(Fe1.8Co0.2)As2, as well as polycrystalline SmFeO0.75F0.2As by means of magneto-optical imaging (MOI) technique. The single crystals were grown out of FeAs flux while polycrystalline sample was grown by hot-press. A MOI film with in-plan magnetization was used to visualize flux distributions at the sample surface. A series of magneto-optical images was taken when the samples were zero-field cooled and field cooled. The flux behavior, including penetration into and expelling from the samples, as well as pinning properties were studied. When external fields increase, …

Reduction Of Superconducting Transition Temperature And Flux Pinning In Al And C Codoped Mgb2 With Insight From First-Principles Calculations, Aihua Li, Xiaolin Wang, S X. Dou, Qiwen Yao, Zhenxiang Cheng, Saeid Soltanian, J M. Yoo, P Munroe

Shi Xue Dou

We report for the first time the Al and C codoping effect on the structures and superconductivity in MgB₂. It was found that both the lattice parameters and the T_c decreased monotonically with increasing doping level of both Al and C. The T_c dropped to 27.5 and 7 K for x=0.2 and for x =0.4, respectively. The reduction of T_c for the codoping was found to be quicker than for individual Al doping and slower than for individual C doping at the same doping levels. First-principles calculations indicated that the observed decrease in T_{c …}

Flux Dynamics In (Y, Nd)1ba2cu3o7 Superconductors, A S Mahmoud, Josip Horvat, S X. Dou

Shi Xue Dou

The vortex dynamics of (Y, Nd)Ba2Cu3O7−δ ((Y, Nd)123) superconductors have been studied using magnetic relaxation measurements obtained at different sweep rates. The temperature dependence of the dynamic relaxation rate (Q) is found to be not vanishing at T = 0 K, and also showed well developed maxima becoming broader and tending to move to higher temperatures with decreasing magnetic field. At temperatures close to the critical temperature (T c ), Q(T) showed well-developed minima becoming deeper and tending to move to lower temperatures with increasing field. These minima appeared to occur approximately at the same reduced temperature position [ T/T …

Upper Critical Field And Thermally Activated Flux Flow In Lafeaso1-Xfx, Mahboobeh Shahbazi, Xiaolin Wang, C Shekhar, O N. Srivastava, Z W. Lin, J G. Zhu, S. X. Dou

Shi Xue Dou

The magneto-resistance, critical current density, Jc, upper critical field, Hc2, and flux pinning properties of LaFeAsO1−xFx superconductors were investigated systematically by magnetic and magneto-transport measurements in the fields up to 13 T over a temperature range of 5–35 K. It was found that the Hc2 increased with increasing fluorine concentration up to x ≤ 0.15, while with higher fluorine doping, Hc2 decreased. A peak effect in the Jc as a function of field was observed at T  Uo, scales as Uo/kB ∝ B−n with n = 0.13 for B n =− 0.68 for B > 1 T for LaFeAsO0.85F0.15.

Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic

Shi Xue Dou

We have systematically studied the flux pinning behavior of MgB2 bulks synthesized by direct diffusion of Mg into pressed pellets of high purity crystalline B powder, with and without mixing with C and SiC nanoparticles, at a reaction temperature of 850degC for 10 hrs. All of the samples showed very high purity and high density, but their microstructure and flux pinning behavior showed significant differences. It was found that the pure MgB2 agrees with the deltaTc pinning model, nano-C doped MgB2 agrees with the deltal pinning model, while the SiC+MgB2 composite agrees with the deltaepsiv pinning model (stress/strain field pinning), …

Very Strong Intrinsic Flux Pinning And Vortex Avalanches In (Ba, K)Fe2as2 Superconducting Single Crystals, Xiaolin Wang, Shaban R. Ghorbani, Sung-Ik Lee, S X. Dou, C T Lin, T H. Johansen, K.H Muller, Zhenxiang Cheng, Germanas Peleckis, M Shabazi, A.J Qviller, V Yurchenko, G.L Sun, D.L Sun

Shi Xue Dou

We report that the (Ba,K)Fe2As2 crystal with Tc=32 K shows a pinning potential, U0, as high as 104 K, with U0 showing very little field dependence. The (Ba,K)Fe2As2 single crystals become isotropic at low temperatures and high magnetic fields, resulting in a very rigid vortex lattice, even in fields very close to Hc2. The isotropic rigid vortices observed in the two-dimensional (2D) (Ba,K)Fe2As2 distinguish this compound from 2D high-Tc cuprate superconductors with 2D vortices. The vortex avalanches were also observed at low temperatures in the (Ba,K)Fe2As2 crystal. It is proposed that it is the K substitution that induces both almost …

Flux Pinning And Vortex Transitions In Doped Bafe2as2 Single Crystals, S R. Ghorbani, X L. Wang, M Shabazi, S X. Dou, K Y. Choi, C T. Lin

Shi Xue Dou

The vortex liquid-to-glass transition has been studied in Ba0.72K0.28Fe2As2 (BaK-122), Ba(Fe0.91Co0.09)2As2(BaCo-122), and Ba(Fe0.95Ni0.05)2As2(BaNi-122) single crystal with superconducting transition temperature, Tc=31.7, 17.3, and 18 K, respectively, by magnetoresistance measurements. For temperatures below Tc, the resistivity curves were measured in magnetic fields within the range of 0≤B≤13 T, and the pinning potential was scaled according to a modified model for vortex liquid resistivity. Good scaling of the resistivity q(B, T) and the effective pinning energy U0(B,T) were obtained. The vortex state is three-dimensional at temperatures lower than a characteristic temperature T*. The vortex phase diagram was determined based on the evolution of …

Kinetic Roughening Of Magnetic Flux Penetration In Mgb2 Thin Films, Andrea Lucarelli, Stephanie Hummert, Andrea Chaney, Gunter Lupke, Brian Moeckly, Yue Zhao, S X. Dou

Shi Xue Dou

Time-resolved magneto-optical studies are performed on MgB2 thin film samples grown by in situ pulsed laser deposition and in situ reactive deposition technique. The latter reveal dendritic avalanche-free flux penetration. The kinetic roughening of magnetic flux penetration is studied for applied ac current. Dynamic scaling laws determined for both static field and ac current are consistent with the directed percolation depinning model, placing the vortex dynamics in MgB2 in the same universality class as YBCO and Nb.