High palaeolatitude record of Late Maastrichtian – Early Danian climate change, Seymour Island, Antarctica

The Latest Cretaceous period was characterised by global cooling, superimposed on this pattern of climate change were perturbations in global climate. In high palaeolatitude settings in the Southern Hemisphere short term glacial episodes may have occurred through the latest Cretaceous. The extensive sedimentary succession within the James Ross Basin, Antarctica, provided an opportunity to test the possibility of late Cretaceous glaciation in particular through the succession exposed on Seymour Island. A high resolution oxygen and carbon stable isotope record through the Late Maastrichtian – Early Danian was generated by analysing diagenetically unaltered aragonite nacre shell material from a molluscan fauna collected from the López de Bertodano Fm., part of the Marambio Group present on Seymour Island, Antarctica. The Marambio Group forms an extensive 1100 m thick Late Maastrichtian section that crops out over ~70 km2 of the southernmost part of the island. Coverage of stable isotope data for the measured stratigraphy was good with 213 screened analyses that included data from within 1 m of the K-Pg boundary located at 1029 m above datum, determined from the first occurrence of the dinoflagellate cyst Senegalinium obscurum. Stable isotope data (‰ VPDB) for primary aragonite from bivalves, cephalopods and gastropods exhibited screened stable isotope data ranges of -0.06 to +2.05‰ for δ18O and -7.54 to +3.7‰ for δ13C. Data showed that at individual stratigraphic levels the range in measured δ18O exhibited significant variability. Benthic specimens provided the majority of the stable isotope data, bivalves exhibited the widest range of δ18O and δ13C values. Data show that individual specimens from the same genus can exhibit significant variability for δ18O and δ13C and that analysis of single samples at discrete stratigraphic levels may provide an erroneous interpretation of climate change. Higher oxygen isotope values were seen mid-section and complement previous records of periods of cooler climate identified from palynology, clumped isotopes and sea level. Palaeotemperatures were calculated for δ18O values for a seawater composition of SMOW = -1.0‰, representing an ice free ocean, 6 to 14°C for bivalves, 9 to 12°C for gastropods and 9 to 15°C for cephalopods. Temperatures indicated relatively stable benthic temperatures (~10°C) with a cooling phase that commenced at ~450 m (~69.5 Ma) with the coolest temperatures developed at ~630 m (~69 Ma). Cooling trends showed a good correlation with the position of seawater lowstands. Thereafter temperatures recovered towards the K-Pg boundary before a cooling trend developed that closely correlated with the PaDa1 lowstand. Acceptance of Deccan Traps volcanism as a causal mechanism for the limited degree of observed warming close to the K-Pg event was limited by a lack of suitable specimens

Ransomware - A Strategic Threat to Organizations

Ransomware is a strategic threat to government, business, and academic organizations. It has both short term and long term consequences, requiring strategic planning to create defenses, assess options, and create policies. The purpose of the study is to answer three questions: What is the strategic risk of cyberattack to organizations? What are the current attitudes and practices of executives who are vulnerable to such threats? What are specific options that organizations should consider to prevent and deal with possible incidents in the future? The article is thus comprised of the following components: A) a history of the development and complexity of ransomware; B) a survey of IT professionals in government, business and education; and C) recommended strategic options for organizations to defend against cyber threats. We conducted a survey of ninety-two cybersecurity professionals in government, education, and business. Attitudinal divergence occurred in the areas of cyber-defense, perpetrator negotiations, ransom payment, and involvement of law enforcement. The authors recommend thirteen specific solutions to assist organizations when dealing with ransomware

Integrating Systems Health Management with Adaptive Controls for a Utility-Scale Wind Turbine

Increasing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. Systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage. Advanced adaptive controls can provide the mechanism to enable optimized operations that also provide the enabling technology for Systems Health Management goals. The work reported herein explores the integration of condition monitoring of wind turbine blades with contingency management and adaptive controls. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine

Augmented Adaptive Control of a Wind Turbine in the Presence of Structural Modes

Wind turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, potentially causing component fatigue and failure. Two key technology drivers for turbine manufacturers are increasing turbine up time and reducing maintenance costs. Since the trend in wind turbine design is towards larger, more flexible turbines with lower frequency structural modes, manufacturers will want to develop methods to operate in the presence of these modes. Accurate models of the dynamic characteristics of new wind turbines are often not available due to the complexity and expense of the modeling task, making wind turbines ideally suited to adaptive control. In this paper, we develop theory for adaptive control with rejection of disturbances in the presence of modes that inhibit the controller. We use this method to design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the interference of certain structural modes in feedback. The control objective is accomplished by collectively pitching the turbine blades. The adaptive pitch controller for Region 3 is compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller

Modified Adaptive Control for Region 3 Operation in the Presence of Wind Turbine Structural Modes

Many challenges exist for the operation of wind turbines in an efficient manner that is reliable and avoids component fatigue and failure. Turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, possibly causing component fatigue and failure. Wind turbine manufacturers are highly motivated to reduce component fatigue and failure that can lead to loss of revenue due to turbine down time and maintenance costs. The trend in wind turbine design is toward larger, more flexible turbines that are ideally suited to adaptive control methods due to the complexity and expense required to create accurate models of their dynamic characteristics. In this paper, we design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed horizontal axis wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the excitation of structural modes in the wind turbine. The control objective is accomplished by collectively pitching the turbine blades. The adaptive collective pitch controller for Region 3 was compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller. The adaptive controller will demonstrate the ability to regulate generator speed in Region 3, while accommodating gusts, and reducing the excitation of certain structural modes in the wind turbine