Stabilization of Linear Systems Over Gaussian Networks

The problem of remotely stabilizing a noisy linear time invariant plant over a Gaussian relay network is addressed. The network is comprised of a sensor node, a group of relay nodes and a remote controller. The sensor and the relay nodes operate subject to an average transmit power constraint and they can cooperate to communicate the observations of the plant's state to the remote controller. The communication links between all nodes are modeled as Gaussian channels. Necessary as well as sufficient conditions for mean-square stabilization over various network topologies are derived. The sufficient conditions are in general obtained using delay-free linear policies and the necessary conditions are obtained using information theoretic tools. Different settings where linear policies are optimal, asymptotically optimal (in certain parameters of the system) and suboptimal have been identified. For the case with noisy multi-dimensional sources controlled over scalar channels, it is shown that linear time varying policies lead to minimum capacity requirements, meeting the fundamental lower bound. For the case with noiseless sources and parallel channels, non-linear policies which meet the lower bound have been identified

Prefigurative Partaking: Employees’ Environmental Activism in an Energy Utility

This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this record The separation between an ‘inside’ and ‘outside’ of organizational politics has become untenable in a rapidly changing political landscape, where people engage in environmental activism in many different domains. To understand contemporary environmental activism, we situate ourselves empirically within an energy utility, Ordalia [pseudonym], a large corporation active across Europe and heavily criticized by external activists for its carbon emitting operations. By merging Rancière’s method of equality and notion of ‘partaking’ with literature on prefiguration in social movements, we analyse everyday green actions pursued by Ordalia’s employees, which we conceptualize as ‘prefigurative partaking’. By focusing on six characterizing themes of prefigurative partaking – aspirational, individual, professional, critical, loyal and communal – we have found that employee activism is incremental, horizontal and boundaryless. We discuss these findings in relation to recent calls for more fruitful exchanges between social movement theory and organization studies, arguing that Rancière’s conceptualization of politics can help us study actions that span civil society and business. This complements and expands our understanding of environmental activism as a dispersed set of actions that can take place anywhere, and hence also at work.Swedish Energy AgencyBritish Academy Mid-Career Fellowshi

Effects of SI administration staffing and support on SI program outcomes in higher education

Supplemental Instruction (SI) is an internationally recognized learning assistance program used in higher education to support traditionally challenging classes by offering regularly scheduled, peer-led, group study sessions for the students enrolled in the targeted course. This study explored the administrative hours spent on specific SI program constructs (training-related, observation of sessions, planning support, and administrative tasks) and program funding and their relationships with program outcomes (attendance rate for the program, the difference in the average final grades between SI session attendees and non-attendees, and the difference in the rate of Ds, Fs, and withdraws between the SI session attendees and non-attendees). This quantitative study collected data from SI programs at institutions across North America (N=63). Multiple linear regression and correlation were used to examine the relationships between the variables. The regression models and correlation analyses were statistically insignificant, except training-related hours per SI leader was significantly related to the attendance rates for the entire SI program. This result might suggest that training-related hours assist leaders in developing high-quality sessions, thereby increasing attendance percentage. This finding indicates that SI program administrators should enhance their training-related responsibilities per SI leader to increase attendance rates for the program. These findings were limited by small sample size and focus on supervisory constructs while ignoring other factors such as institutional characteristics that may influence program outcomes. Future studies should explore each supervisory construct individually while controlling for aspects of SI programs that may affect program outcomes and collect larger sample sizes.Includes bibliographical reference

Bounds on the Sum-Rate of MIMO Causal Source Coding Systems with Memory under Spatio-Temporal Distortion Constraints

In this paper, we derive lower and upper bounds on the OPTA of a two-user multi-input multi-output (MIMO) causal encoding and causal decoding problem. Each user’s source model is described by a multidimensional Markov source driven by additive i.i.d. noise process subject to three classes of spatio-temporal distortion constraints. To characterize the lower bounds, we use state augmentation techniques and a data processing theorem, which recovers a variant of rate distortion function as an information measure known in the literature as nonanticipatory ϵ-entropy, sequential or nonanticipative RDF. We derive lower bound characterizations for a system driven by an i.i.d. Gaussian noise process, which we solve using the SDP algorithm for all three classes of distortion constraints. We obtain closed form solutions when the system’s noise is possibly non-Gaussian for both users and when only one of the users is described by a source model driven by a Gaussian noise process. To obtain the upper bounds, we use the best linear forward test channel realization that corresponds to the optimal test channel realization when the system is driven by a Gaussian noise process and apply a sequential causal DPCM-based scheme with a feedback loop followed by a scaled ECDQ scheme that leads to upper bounds with certain performance guarantees. Then, we use the linear forward test channel as a benchmark to obtain upper bounds on the OPTA, when the system is driven by an additive i.i.d. non-Gaussian noise process. We support our framework with various simulation studies