Anomalous Geomagnetic Signal Emphasized before the Mw8.2 Coastal Alaska Earthquake,Occurred on 29 July 2021

A very strong earthquake of magnitude Mw8.2 struck the coastal zone of Alaska (USA), on 29 July 2021. This earthquake was felt around the Gulf of Alaska, on a wide offshore area belonging to USA and Canada. In order to identify an anomalous geomagnetic signal before the onset of this earthquake, we retrospectively analyze the data collected on the interval 17 June–31 July 2021, via internet, at the two geomagnetic observatories, College (CMO)—Alaska and Newport (NEW)—USA, by using the polarization parameter (BPOL) and the strain effect related to geomagnetic signal identification. Thus, for both observation sites (CMO and NEW), the daily mean distribution of the BPOL and its standard deviation (STDEV) are carried out using an FFT band-pass filtering in the ULF range (0.001–0.0083 Hz). Further on, a statistical analysis based on a standardized random variable equation is applied to emphasize the following: (a) the anomalous signature related to Mw8.2 earthquake on the both time series BPOL*(CMO) and BPOL*(NEW); (b) the differentiation of the transient local anomalies associated with Mw8.2 earthquake from the internal and external parts of the geomagnetic field, taking the NEW observatory as reference. Finally, on the BPOL*(NEW-CMO) time series, carried out on the interval 7–31 July 2021, a very clear anomaly of maximum, greater than 1.2 STDEV, was detected on 22 July, with 7 days before the onset of the Mw8.2 earthquake.     

Frequency spectra of CFC metals and correlated spectral density between bulk atoms

The Green's function generating coefficients method is applied to the calculation of frequency spectra and correlated spectral density for bulk atoms of copper and platinum. The mean square and mean correlated displacements are then deduced. The method is certainly a powerful tool allowing precise calculation of all quantities related to vibrational properties of solids.     

An integrated AC electrokinetic pump in a microfluidic loop for fast and tunable flow control

We have built a dedicated lab on a chip to study the performance of an integrated electrokinetic micropump, driven by a low voltage AC signal. This micropump consists of an array of interdigitated electrodes and is here integrated in a microfluidic loop. We demonstrate that this device can pump continuously and reproducibly electrolyte solutions of low to moderate ionic strength. The pumping speed reaches up to 500 [micro sign]m s(-1) in 20 [micro sign]m deep and 100 [micro sign]m wide channels with a driving signal in the 1-10 kHz range and an amplitude of only a few volts. In addition, we have observed an interesting reversal of the pumping direction at higher frequencies (50-100 kHz). Our device permits a systematic and automated exploration of the influence of the ionic strength thanks to an integrated micromixer.     

A Piecewise Line-Search Technique for Maintaining the Positive Definitenes of the Matrices in the SQP Method

A technique for maintaining the positive definiteness of the matrices in the quasi-Newton version of the SQP algorithm is proposed. In our algorithm, matrices approximating the Hessian of the augmented Lagrangian are updated. The positive definiteness of these matrices in the space tangent to the constraint manifold is ensured by a so-called piecewise line-search technique, while their positive definiteness in a complementary subspace is obtained by setting the augmentation parameter. In our experiment, the combination of these two ideas leads to a new algorithm that turns out to be more robust and often improves the results obtained with other approaches.     

Integer extended ABS algorithms and possible control of intermediate results for linear Diophantine systems

We present a new class of integer extended ABS algorithms for solving linear Diophantine systems. The proposed class contains the integer ABS (the so-called EMAS and our proposed MEMAS) algorithms and the generalized Rosser’s algorithm as its members. After an application of each member of the class a particular solution of the system and an integer basis for the null space of the coefficient matrix are at hand. We show that effective algorithms exist within this class by appropriately setting the parameters of the members of the new class to control the growth of intermediate results. Finally, we propose two effective heuristic rules for selecting certain parameters in the new class of integer extended ABS algorithms.